Implement Latin1 JsString (#3450)

cli/src/debug/function.rs

@@ -1,6 +1,6 @@
 use boa_engine::{
     builtins::function::OrdinaryFunction,
-    js_string,
+    js_str, js_string,
     object::ObjectInitializer,
     vm::flowgraph::{Direction, Graph},
     Context, JsArgs, JsNativeError, JsObject, JsResult, JsValue, NativeFunction,
@@ -68,10 +68,9 @@ fn flowgraph(_this: &JsValue, args: &[JsValue], context: &mut Context) -> JsResu
     let mut direction = Direction::LeftToRight;
     if let Some(arguments) = args.get(1) {
         if let Some(arguments) = arguments.as_object() {
-            format = flowgraph_parse_format_option(&arguments.get(js_string!("format"), context)?)?;
-            direction = flowgraph_parse_direction_option(
-                &arguments.get(js_string!("direction"), context)?,
-            )?;
+            format = flowgraph_parse_format_option(&arguments.get(js_str!("format"), context)?)?;
+            direction =
+                flowgraph_parse_direction_option(&arguments.get(js_str!("direction"), context)?)?;
         } else if value.is_string() {
             format = flowgraph_parse_format_option(value)?;
         } else {

cli/src/debug/limits.rs

@@ -1,5 +1,5 @@
 use boa_engine::{
-    js_string,
+    js_str,
     object::{FunctionObjectBuilder, ObjectInitializer},
     property::Attribute,
     Context, JsArgs, JsNativeError, JsObject, JsResult, JsValue, NativeFunction,
@@ -51,51 +51,51 @@ fn set_recursion(_: &JsValue, args: &[JsValue], context: &mut Context) -> JsResu
 pub(super) fn create_object(context: &mut Context) -> JsObject {
     let get_loop =
         FunctionObjectBuilder::new(context.realm(), NativeFunction::from_fn_ptr(get_loop))
-            .name("get loop")
+            .name(js_str!("get loop"))
             .length(0)
             .build();
     let set_loop =
         FunctionObjectBuilder::new(context.realm(), NativeFunction::from_fn_ptr(set_loop))
-            .name("set loop")
+            .name(js_str!("set loop"))
             .length(1)
             .build();
 
     let get_stack =
         FunctionObjectBuilder::new(context.realm(), NativeFunction::from_fn_ptr(get_stack))
-            .name("get stack")
+            .name(js_str!("get stack"))
             .length(0)
             .build();
     let set_stack =
         FunctionObjectBuilder::new(context.realm(), NativeFunction::from_fn_ptr(set_stack))
-            .name("set stack")
+            .name(js_str!("set stack"))
             .length(1)
             .build();
 
     let get_recursion =
         FunctionObjectBuilder::new(context.realm(), NativeFunction::from_fn_ptr(get_recursion))
-            .name("get recursion")
+            .name(js_str!("get recursion"))
             .length(0)
             .build();
     let set_recursion =
         FunctionObjectBuilder::new(context.realm(), NativeFunction::from_fn_ptr(set_recursion))
-            .name("set recursion")
+            .name(js_str!("set recursion"))
             .length(1)
             .build();
     ObjectInitializer::new(context)
         .accessor(
-            js_string!("loop"),
+            js_str!("loop"),
             Some(get_loop),
             Some(set_loop),
             Attribute::WRITABLE | Attribute::CONFIGURABLE | Attribute::NON_ENUMERABLE,
         )
         .accessor(
-            js_string!("stack"),
+            js_str!("stack"),
             Some(get_stack),
             Some(set_stack),
             Attribute::WRITABLE | Attribute::CONFIGURABLE | Attribute::NON_ENUMERABLE,
         )
         .accessor(
-            js_string!("recursion"),
+            js_str!("recursion"),
             Some(get_recursion),
             Some(set_recursion),
             Attribute::WRITABLE | Attribute::CONFIGURABLE | Attribute::NON_ENUMERABLE,

cli/src/debug/mod.rs

@@ -1,7 +1,7 @@
 // Allow lint so it, doesn't warn about `JsResult<>` unneeded return on functions.
 #![allow(clippy::unnecessary_wraps)]
 
-use boa_engine::{js_string, object::ObjectInitializer, property::Attribute, Context, JsObject};
+use boa_engine::{js_str, object::ObjectInitializer, property::Attribute, Context, JsObject};
 
 mod function;
 mod gc;
@@ -10,6 +10,7 @@ mod object;
 mod optimizer;
 mod realm;
 mod shape;
+mod string;
 
 fn create_boa_object(context: &mut Context) -> JsObject {
     let function_module = function::create_object(context);
@@ -19,43 +20,49 @@ fn create_boa_object(context: &mut Context) -> JsObject {
     let gc_module = gc::create_object(context);
     let realm_module = realm::create_object(context);
     let limits_module = limits::create_object(context);
+    let string_module = string::create_string(context);
 
     ObjectInitializer::new(context)
         .property(
-            js_string!("function"),
+            js_str!("function"),
             function_module,
             Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
         )
         .property(
-            js_string!("object"),
+            js_str!("object"),
             object_module,
             Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
         )
         .property(
-            js_string!("shape"),
+            js_str!("shape"),
             shape_module,
             Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
         )
         .property(
-            js_string!("optimizer"),
+            js_str!("optimizer"),
             optimizer_module,
             Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
         )
         .property(
-            js_string!("gc"),
+            js_str!("gc"),
             gc_module,
             Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
         )
         .property(
-            js_string!("realm"),
+            js_str!("realm"),
             realm_module,
             Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
         )
         .property(
-            js_string!("limits"),
+            js_str!("limits"),
             limits_module,
             Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
         )
+        .property(
+            js_str!("string"),
+            string_module,
+            Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
+        )
         .build()
 }
 
@@ -64,7 +71,7 @@ pub(crate) fn init_boa_debug_object(context: &mut Context) {
     let boa_object = create_boa_object(context);
     context
         .register_global_property(
-            js_string!("$boa"),
+            js_str!("$boa"),
             boa_object,
             Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
         )

cli/src/debug/optimizer.rs

@@ -1,5 +1,5 @@
 use boa_engine::{
-    js_string,
+    js_str,
     object::{FunctionObjectBuilder, ObjectInitializer},
     optimizer::OptimizerOptions,
     property::Attribute,
@@ -64,13 +64,13 @@ pub(super) fn create_object(context: &mut Context) -> JsObject {
             .build();
     ObjectInitializer::new(context)
         .accessor(
-            js_string!("constantFolding"),
+            js_str!("constantFolding"),
             Some(get_constant_folding),
             Some(set_constant_folding),
             Attribute::WRITABLE | Attribute::CONFIGURABLE | Attribute::NON_ENUMERABLE,
         )
         .accessor(
-            js_string!("statistics"),
+            js_str!("statistics"),
             Some(get_statistics),
             Some(set_statistics),
             Attribute::WRITABLE | Attribute::CONFIGURABLE | Attribute::NON_ENUMERABLE,

cli/src/debug/string.rs

@@ -0,0 +1,93 @@
+use boa_engine::{
+    js_string, object::ObjectInitializer, property::Attribute, string::JsStrVariant, Context,
+    JsNativeError, JsObject, JsResult, JsValue, NativeFunction,
+};
+
+fn storage(_: &JsValue, args: &[JsValue], _: &mut Context) -> JsResult<JsValue> {
+    let Some(value) = args.first() else {
+        return Err(JsNativeError::typ()
+            .with_message("expected string argument")
+            .into());
+    };
+
+    let Some(string) = value.as_string() else {
+        return Err(JsNativeError::typ()
+            .with_message(format!("expected string, got {}", value.type_of()))
+            .into());
+    };
+
+    let storage = if string.is_static() { "static" } else { "heap" };
+    Ok(js_string!(storage).into())
+}
+
+fn encoding(_: &JsValue, args: &[JsValue], _: &mut Context) -> JsResult<JsValue> {
+    let Some(value) = args.first() else {
+        return Err(JsNativeError::typ()
+            .with_message("expected string argument")
+            .into());
+    };
+
+    let Some(string) = value.as_string() else {
+        return Err(JsNativeError::typ()
+            .with_message(format!("expected string, got {}", value.type_of()))
+            .into());
+    };
+
+    let str = string.as_str();
+    let encoding = match str.variant() {
+        JsStrVariant::Latin1(_) => "latin1",
+        JsStrVariant::Utf16(_) => "utf16",
+    };
+    Ok(js_string!(encoding).into())
+}
+
+fn summary(_: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
+    let Some(value) = args.first() else {
+        return Err(JsNativeError::typ()
+            .with_message("expected string argument")
+            .into());
+    };
+
+    let Some(string) = value.as_string() else {
+        return Err(JsNativeError::typ()
+            .with_message(format!("expected string, got {}", value.type_of()))
+            .into());
+    };
+
+    let storage = if string.is_static() { "static" } else { "heap" };
+    let encoding = match string.as_str().variant() {
+        JsStrVariant::Latin1(_) => "latin1",
+        JsStrVariant::Utf16(_) => "utf16",
+    };
+
+    let summary = ObjectInitializer::new(context)
+        .property(js_string!("storage"), js_string!(storage), Attribute::all())
+        .property(
+            js_string!("encoding"),
+            js_string!(encoding),
+            Attribute::all(),
+        )
+        .build();
+
+    Ok(summary.into())
+}
+
+pub(super) fn create_string(context: &mut Context) -> JsObject {
+    ObjectInitializer::new(context)
+        .function(
+            NativeFunction::from_fn_ptr(storage),
+            js_string!("storage"),
+            1,
+        )
+        .function(
+            NativeFunction::from_fn_ptr(encoding),
+            js_string!("encoding"),
+            1,
+        )
+        .function(
+            NativeFunction::from_fn_ptr(summary),
+            js_string!("summary"),
+            1,
+        )
+        .build()
+}

core/engine/src/bigint.rs

@@ -1,6 +1,6 @@
 //! Boa's implementation of ECMAScript's bigint primitive type.
 
-use crate::{builtins::Number, error::JsNativeError, JsData, JsResult};
+use crate::{builtins::Number, error::JsNativeError, JsData, JsResult, JsString};
 use boa_gc::{Finalize, Trace};
 use num_integer::Integer;
 use num_traits::{pow::Pow, FromPrimitive, One, ToPrimitive, Zero};
@@ -89,6 +89,22 @@ impl JsBigInt {
         })
     }
 
+    /// Abstract operation `StringToBigInt ( str )`
+    ///
+    /// More information:
+    /// - [ECMAScript reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-stringtobigint
+    pub(crate) fn from_js_string(string: &JsString) -> Option<JsBigInt> {
+        // 1. Let text be ! StringToCodePoints(str).
+        // 2. Let literal be ParseText(text, StringIntegerLiteral).
+        // 3. If literal is a List of errors, return undefined.
+        // 4. Let mv be the MV of literal.
+        // 5. Assert: mv is an integer.
+        // 6. Return ℤ(mv).
+        JsBigInt::from_string(string.to_std_string().ok().as_ref()?)
+    }
+
     /// This function takes a string and converts it to `BigInt` type.
     ///
     /// More information:

core/engine/src/builtins/array/array_iterator.rs

@@ -20,6 +20,7 @@ use crate::{
     Context, JsData, JsResult,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 /// The Array Iterator object represents an iteration over an array. It implements the iterator protocol.
@@ -52,7 +53,7 @@ impl IntrinsicObject for ArrayIterator {
             .static_method(Self::next, js_string!("next"), 0)
             .static_property(
                 JsSymbol::to_string_tag(),
-                js_string!("Array Iterator"),
+                js_str!("Array Iterator"),
                 Attribute::CONFIGURABLE,
             )
             .build();

core/engine/src/builtins/array/mod.rs

@@ -10,7 +10,7 @@
 //! [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
 
 use boa_gc::{Finalize, Trace};
-use boa_macros::utf16;
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use thin_vec::ThinVec;
 
@@ -161,12 +161,12 @@ impl IntrinsicObject for Array {
             .method(Self::unshift, js_string!("unshift"), 1)
             .method(Self::with, js_string!("with"), 2)
             .property(
-                utf16!("toString"),
+                js_string!("toString"),
                 to_string_function,
                 Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
             )
             .property(
-                utf16!("values"),
+                js_string!("values"),
                 values_function.clone(),
                 Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
             )
@@ -1012,7 +1012,7 @@ impl Array {
         for k in 0..len {
             // a. If k > 0, set R to the string-concatenation of R and sep.
             if k > 0 {
-                r.extend_from_slice(&separator);
+                r.push(separator.clone());
             }
             // b. Let element be ? Get(O, ! ToString(𝔽(k))).
             let element = o.get(k, context)?;
@@ -1023,7 +1023,7 @@ impl Array {
                 element.to_string(context)?
             };
             // d. Set R to the string-concatenation of R and next.
-            r.extend_from_slice(&next);
+            r.push(next.clone());
             // e. Set k to k + 1.
         }
         // 8. Return R.
@@ -1051,7 +1051,7 @@ impl Array {
         // 1. Let array be ? ToObject(this value).
         let array = this.to_object(context)?;
         // 2. Let func be ? Get(array, "join").
-        let func = array.get(utf16!("join"), context)?;
+        let func = array.get(js_string!("join"), context)?;
         // 3. If IsCallable(func) is false, set func to the intrinsic function %Object.prototype.toString%.
         // 4. Return ? Call(func, array).
         if let Some(func) = func.as_callable() {
@@ -2203,12 +2203,12 @@ impl Array {
             #[cfg(feature = "intl")]
             {
                 // TODO: this should eventually return a locale-sensitive separator.
-                utf16!(", ")
+                js_str!(", ")
             }
 
             #[cfg(not(feature = "intl"))]
             {
-                utf16!(", ")
+                js_str!(", ")
             }
         };
 
@@ -2221,7 +2221,7 @@ impl Array {
             // a. If k > 0, then
             if k > 0 {
                 // i. Set R to the string-concatenation of R and separator.
-                r.extend_from_slice(separator);
+                r.extend(separator.iter());
             }
 
             // b. Let nextElement be ? Get(array, ! ToString(k)).
@@ -2231,16 +2231,16 @@ impl Array {
             if !next.is_null_or_undefined() {
                 // i. Let S be ? ToString(? Invoke(nextElement, "toLocaleString", « locales, options »)).
                 let s = next
-                    .invoke(utf16!("toLocaleString"), args, context)?
+                    .invoke(js_str!("toLocaleString"), args, context)?
                     .to_string(context)?;
 
                 // ii. Set R to the string-concatenation of R and S.
-                r.extend_from_slice(&s);
+                r.extend(s.iter());
             }
             //     d. Increase k by 1.
         }
         // 7. Return R.
-        Ok(js_string!(r).into())
+        Ok(js_string!(&r[..]).into())
     }
 
     /// Gets the delete count of a splice operation.
@@ -3304,37 +3304,37 @@ impl Array {
         {
             let mut obj = unscopable_list.borrow_mut();
             // 2. Perform ! CreateDataPropertyOrThrow(unscopableList, "at", true).
-            obj.insert(utf16!("at"), true_prop.clone());
+            obj.insert(js_str!("at"), true_prop.clone());
             // 3. Perform ! CreateDataPropertyOrThrow(unscopableList, "copyWithin", true).
-            obj.insert(utf16!("copyWithin"), true_prop.clone());
+            obj.insert(js_str!("copyWithin"), true_prop.clone());
             // 4. Perform ! CreateDataPropertyOrThrow(unscopableList, "entries", true).
-            obj.insert(utf16!("entries"), true_prop.clone());
+            obj.insert(js_str!("entries"), true_prop.clone());
             // 5. Perform ! CreateDataPropertyOrThrow(unscopableList, "fill", true).
-            obj.insert(utf16!("fill"), true_prop.clone());
+            obj.insert(js_str!("fill"), true_prop.clone());
             // 6. Perform ! CreateDataPropertyOrThrow(unscopableList, "find", true).
-            obj.insert(utf16!("find"), true_prop.clone());
+            obj.insert(js_str!("find"), true_prop.clone());
             // 7. Perform ! CreateDataPropertyOrThrow(unscopableList, "findIndex", true).
-            obj.insert(utf16!("findIndex"), true_prop.clone());
+            obj.insert(js_str!("findIndex"), true_prop.clone());
             // 8. Perform ! CreateDataPropertyOrThrow(unscopableList, "findLast", true).
-            obj.insert(utf16!("findLast"), true_prop.clone());
+            obj.insert(js_str!("findLast"), true_prop.clone());
             // 9. Perform ! CreateDataPropertyOrThrow(unscopableList, "findLastIndex", true).
-            obj.insert(utf16!("findLastIndex"), true_prop.clone());
+            obj.insert(js_str!("findLastIndex"), true_prop.clone());
             // 10. Perform ! CreateDataPropertyOrThrow(unscopableList, "flat", true).
-            obj.insert(utf16!("flat"), true_prop.clone());
+            obj.insert(js_str!("flat"), true_prop.clone());
             // 11. Perform ! CreateDataPropertyOrThrow(unscopableList, "flatMap", true).
-            obj.insert(utf16!("flatMap"), true_prop.clone());
+            obj.insert(js_str!("flatMap"), true_prop.clone());
             // 12. Perform ! CreateDataPropertyOrThrow(unscopableList, "includes", true).
-            obj.insert(utf16!("includes"), true_prop.clone());
+            obj.insert(js_str!("includes"), true_prop.clone());
             // 13. Perform ! CreateDataPropertyOrThrow(unscopableList, "keys", true).
-            obj.insert(utf16!("keys"), true_prop.clone());
+            obj.insert(js_str!("keys"), true_prop.clone());
             // 14. Perform ! CreateDataPropertyOrThrow(unscopableList, "toReversed", true).
-            obj.insert(utf16!("toReversed"), true_prop.clone());
+            obj.insert(js_str!("toReversed"), true_prop.clone());
             // 15. Perform ! CreateDataPropertyOrThrow(unscopableList, "toSorted", true).
-            obj.insert(utf16!("toSorted"), true_prop.clone());
+            obj.insert(js_str!("toSorted"), true_prop.clone());
             // 16. Perform ! CreateDataPropertyOrThrow(unscopableList, "toSpliced", true).
-            obj.insert(utf16!("toSpliced"), true_prop.clone());
+            obj.insert(js_str!("toSpliced"), true_prop.clone());
             // 17. Perform ! CreateDataPropertyOrThrow(unscopableList, "values", true).
-            obj.insert(utf16!("values"), true_prop);
+            obj.insert(js_str!("values"), true_prop);
         }
 
         // 13. Return unscopableList.

core/engine/src/builtins/array/tests.rs

@@ -2,6 +2,7 @@ use super::Array;
 use crate::{
     builtins::Number, js_string, run_test_actions, Context, JsNativeErrorKind, JsValue, TestAction,
 };
+use boa_macros::js_str;
 use indoc::indoc;
 
 #[test]
@@ -38,7 +39,7 @@ fn of() {
         TestAction::assert("arrayEquals(Array.of(), [])"),
         TestAction::run("let a = Array.of.call(Date, 'a', undefined, 3);"),
         TestAction::assert("a instanceof Date"),
-        TestAction::assert_eq("a[0]", js_string!("a")),
+        TestAction::assert_eq("a[0]", js_str!("a")),
         TestAction::assert_eq("a[1]", JsValue::undefined()),
         TestAction::assert_eq("a[2]", 3),
         TestAction::assert_eq("a.length", 3),
@@ -75,9 +76,9 @@ fn copy_within() {
 fn join() {
     run_test_actions([
         TestAction::assert_eq("[].join('.')", js_string!()),
-        TestAction::assert_eq("['a'].join('.')", js_string!("a")),
-        TestAction::assert_eq("['a', 'b', 'c'].join('.')", js_string!("a.b.c")),
-        TestAction::assert_eq("let a=[];a[0]=a;a[1]=a;a[2]=a;a.join()", js_string!(",,")),
+        TestAction::assert_eq("['a'].join('.')", js_str!("a")),
+        TestAction::assert_eq("['a', 'b', 'c'].join('.')", js_str!("a.b.c")),
+        TestAction::assert_eq("let a=[];a[0]=a;a[1]=a;a[2]=a;a.join()", js_str!(",,")),
     ]);
 }
 
@@ -85,8 +86,8 @@ fn join() {
 fn to_string() {
     run_test_actions([
         TestAction::assert_eq("[].toString()", js_string!()),
-        TestAction::assert_eq("['a'].toString()", js_string!("a")),
-        TestAction::assert_eq("['a', 'b', 'c'].toString()", js_string!("a,b,c")),
+        TestAction::assert_eq("['a'].toString()", js_str!("a")),
+        TestAction::assert_eq("['a', 'b', 'c'].toString()", js_str!("a,b,c")),
     ]);
 }
 
@@ -116,7 +117,7 @@ fn every() {
 fn find() {
     run_test_actions([TestAction::assert_eq(
         "['a', 'b', 'c'].find(e => e == 'a')",
-        js_string!("a"),
+        js_str!("a"),
     )]);
 }
 
@@ -350,7 +351,7 @@ fn fill_obj_ref() {
                 let a = new Array(3).fill(obj);
                 obj.hi = 'hi'
             "#}),
-        TestAction::assert_eq("a[2].hi", js_string!("hi")),
+        TestAction::assert_eq("a[2].hi", js_str!("hi")),
     ]);
 }
 

core/engine/src/builtins/async_generator/mod.rs

@@ -7,8 +7,10 @@
 
 use crate::{
     builtins::{
-        generator::GeneratorContext, iterable::create_iter_result_object,
-        promise::if_abrupt_reject_promise, promise::PromiseCapability, Promise,
+        generator::GeneratorContext,
+        iterable::create_iter_result_object,
+        promise::{if_abrupt_reject_promise, PromiseCapability},
+        Promise,
     },
     context::intrinsics::Intrinsics,
     error::JsNativeError,
@@ -576,7 +578,7 @@ impl AsyncGenerator {
                 generator.clone(),
             ),
         )
-        .name("")
+        .name(js_string!(""))
         .length(1)
         .build();
 
@@ -611,7 +613,7 @@ impl AsyncGenerator {
                 generator,
             ),
         )
-        .name("")
+        .name(js_string!(""))
         .length(1)
         .build();
 

core/engine/src/builtins/atomics/mod.rs

@@ -21,6 +21,7 @@ use crate::{
     JsString, JsValue,
 };
 
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 use super::{
@@ -463,9 +464,9 @@ impl Atomics {
         };
 
         Ok(match result {
-            futex::AtomicsWaitResult::NotEqual => js_string!("not-equal"),
-            futex::AtomicsWaitResult::TimedOut => js_string!("timed-out"),
-            futex::AtomicsWaitResult::Ok => js_string!("ok"),
+            futex::AtomicsWaitResult::NotEqual => js_str!("not-equal"),
+            futex::AtomicsWaitResult::TimedOut => js_str!("timed-out"),
+            futex::AtomicsWaitResult::Ok => js_str!("ok"),
         }
         .into())
     }

core/engine/src/builtins/bigint/tests.rs

@@ -1,4 +1,6 @@
-use crate::{js_string, run_test_actions, JsBigInt, JsNativeErrorKind, TestAction};
+use boa_macros::js_str;
+
+use crate::{run_test_actions, JsBigInt, JsNativeErrorKind, TestAction};
 
 #[test]
 fn equality() {
@@ -147,10 +149,10 @@ fn operations() {
 #[test]
 fn to_string() {
     run_test_actions([
-        TestAction::assert_eq("1000n.toString()", js_string!("1000")),
-        TestAction::assert_eq("1000n.toString(2)", js_string!("1111101000")),
-        TestAction::assert_eq("255n.toString(16)", js_string!("ff")),
-        TestAction::assert_eq("1000n.toString(36)", js_string!("rs")),
+        TestAction::assert_eq("1000n.toString()", js_str!("1000")),
+        TestAction::assert_eq("1000n.toString(2)", js_str!("1111101000")),
+        TestAction::assert_eq("255n.toString(16)", js_str!("ff")),
+        TestAction::assert_eq("1000n.toString(36)", js_str!("rs")),
     ]);
 }
 

core/engine/src/builtins/builder.rs

@@ -1,4 +1,4 @@
-use boa_macros::utf16;
+use boa_macros::js_str;
 
 use crate::{
     js_string,
@@ -115,7 +115,7 @@ impl<S: ApplyToObject + IsConstructor> ApplyToObject for Callable<S> {
                 .configurable(true),
         );
         object.insert(
-            utf16!("name"),
+            js_str!("name"),
             PropertyDescriptor::builder()
                 .value(self.name)
                 .writable(false)
@@ -363,8 +363,8 @@ impl BuiltInConstructorWithPrototype<'_> {
         let length = self.length;
         let name = self.name.clone();
         let prototype = self.prototype.clone();
-        self = self.static_property(js_string!("length"), length, Attribute::CONFIGURABLE);
-        self = self.static_property(js_string!("name"), name, Attribute::CONFIGURABLE);
+        self = self.static_property(js_str!("length"), length, Attribute::CONFIGURABLE);
+        self = self.static_property(js_str!("name"), name, Attribute::CONFIGURABLE);
         self = self.static_property(PROTOTYPE, prototype, Attribute::empty());
 
         let attributes = self.attributes;
@@ -411,8 +411,8 @@ impl BuiltInConstructorWithPrototype<'_> {
     pub(crate) fn build_without_prototype(mut self) {
         let length = self.length;
         let name = self.name.clone();
-        self = self.static_property(js_string!("length"), length, Attribute::CONFIGURABLE);
-        self = self.static_property(js_string!("name"), name, Attribute::CONFIGURABLE);
+        self = self.static_property(js_str!("length"), length, Attribute::CONFIGURABLE);
+        self = self.static_property(js_str!("name"), name, Attribute::CONFIGURABLE);
 
         let mut object = self.object.borrow_mut();
         let function = object
@@ -483,7 +483,7 @@ impl<'ctx> BuiltInBuilder<'ctx, OrdinaryObject> {
             realm,
             function,
             length: 0,
-            name: js_string!(""),
+            name: js_string!(),
         }
     }
 
@@ -496,7 +496,7 @@ impl<'ctx> BuiltInBuilder<'ctx, OrdinaryObject> {
             object: I::get(realm.intrinsics()),
             kind: Callable {
                 function,
-                name: js_string!(""),
+                name: js_string!(),
                 length: 0,
                 kind: OrdinaryFunction,
                 realm: realm.clone(),
@@ -515,7 +515,7 @@ impl<'ctx> BuiltInBuilder<'ctx, OrdinaryObject> {
             object,
             kind: Callable {
                 function,
-                name: js_string!(""),
+                name: js_string!(),
                 length: 0,
                 kind: OrdinaryFunction,
                 realm: realm.clone(),

core/engine/src/builtins/date/mod.rs

@@ -27,12 +27,13 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     symbol::JsSymbol,
     value::{JsValue, PreferredType},
     Context, JsArgs, JsData, JsError, JsResult, JsString,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 pub(crate) mod utils;
@@ -1416,34 +1417,40 @@ impl Date {
         //    including all format elements and the UTC offset representation "Z".
         let year = year_from_time(tv);
         let year = if year.is_positive() && year >= 10000 {
-            js_string!(utf16!("+"), &pad_six(year.unsigned_abs()))
+            js_string!(js_str!("+"), pad_six(year.unsigned_abs(), &mut [0; 6]))
         } else if year.is_positive() {
-            JsString::from(&pad_four(year.unsigned_abs()))
+            pad_four(year.unsigned_abs(), &mut [0; 4]).into()
         } else {
-            js_string!(utf16!("-"), &pad_six(year.unsigned_abs()))
+            js_string!(js_str!("-"), pad_six(year.unsigned_abs(), &mut [0; 6]))
         };
-        let month = pad_two(month_from_time(tv) + 1);
-        let day = pad_two(date_from_time(tv));
-        let hour = pad_two(hour_from_time(tv));
-        let minute = pad_two(min_from_time(tv));
-        let second = pad_two(sec_from_time(tv));
-        let millisecond = pad_three(ms_from_time(tv));
+        let mut binding = [0; 2];
+        let month = pad_two(month_from_time(tv) + 1, &mut binding);
+        let mut binding = [0; 2];
+        let day = pad_two(date_from_time(tv), &mut binding);
+        let mut binding = [0; 2];
+        let hour = pad_two(hour_from_time(tv), &mut binding);
+        let mut binding = [0; 2];
+        let minute = pad_two(min_from_time(tv), &mut binding);
+        let mut binding = [0; 2];
+        let second = pad_two(sec_from_time(tv), &mut binding);
+        let mut binding = [0; 3];
+        let millisecond = pad_three(ms_from_time(tv), &mut binding);
 
         Ok(JsValue::from(js_string!(
             &year,
-            utf16!("-"),
-            &month,
-            utf16!("-"),
-            &day,
-            utf16!("T"),
-            &hour,
-            utf16!(":"),
-            &minute,
-            utf16!(":"),
-            &second,
-            utf16!("."),
-            &millisecond,
-            utf16!("Z")
+            js_str!("-"),
+            month,
+            js_str!("-"),
+            day,
+            js_str!("T"),
+            hour,
+            js_str!(":"),
+            minute,
+            js_str!(":"),
+            second,
+            js_str!("."),
+            millisecond,
+            js_str!("Z")
         )))
     }
 
@@ -1473,7 +1480,7 @@ impl Date {
         }
 
         // 4. Return ? Invoke(O, "toISOString").
-        let func = o.get(utf16!("toISOString"), context)?;
+        let func = o.get(js_string!("toISOString"), context)?;
         func.call(this, &[], context)
     }
 
@@ -1632,50 +1639,51 @@ impl Date {
 
         // 5. Let weekday be the Name of the entry in Table 63 with the Number WeekDay(tv).
         let weekday = match week_day(tv) {
-            0 => utf16!("Sun"),
-            1 => utf16!("Mon"),
-            2 => utf16!("Tue"),
-            3 => utf16!("Wed"),
-            4 => utf16!("Thu"),
-            5 => utf16!("Fri"),
-            6 => utf16!("Sat"),
+            0 => js_str!("Sun"),
+            1 => js_str!("Mon"),
+            2 => js_str!("Tue"),
+            3 => js_str!("Wed"),
+            4 => js_str!("Thu"),
+            5 => js_str!("Fri"),
+            6 => js_str!("Sat"),
             _ => unreachable!(),
         };
 
         // 6. Let month be the Name of the entry in Table 64 with the Number MonthFromTime(tv).
         let month = match month_from_time(tv) {
-            0 => utf16!("Jan"),
-            1 => utf16!("Feb"),
-            2 => utf16!("Mar"),
-            3 => utf16!("Apr"),
-            4 => utf16!("May"),
-            5 => utf16!("Jun"),
-            6 => utf16!("Jul"),
-            7 => utf16!("Aug"),
-            8 => utf16!("Sep"),
-            9 => utf16!("Oct"),
-            10 => utf16!("Nov"),
-            11 => utf16!("Dec"),
+            0 => js_str!("Jan"),
+            1 => js_str!("Feb"),
+            2 => js_str!("Mar"),
+            3 => js_str!("Apr"),
+            4 => js_str!("May"),
+            5 => js_str!("Jun"),
+            6 => js_str!("Jul"),
+            7 => js_str!("Aug"),
+            8 => js_str!("Sep"),
+            9 => js_str!("Oct"),
+            10 => js_str!("Nov"),
+            11 => js_str!("Dec"),
             _ => unreachable!(),
         };
 
         // 7. Let day be ToZeroPaddedDecimalString(ℝ(DateFromTime(tv)), 2).
-        let day = pad_two(date_from_time(tv));
+        let mut binding = [0; 2];
+        let day = pad_two(date_from_time(tv), &mut binding);
 
         // 8. Let yv be YearFromTime(tv).
         let yv = year_from_time(tv);
 
         // 9. If yv is +0𝔽 or yv > +0𝔽, let yearSign be the empty String; otherwise, let yearSign be "-".
-        let year_sign = if yv >= 0 { utf16!("") } else { utf16!("-") };
+        let year_sign = if yv >= 0 { js_str!("") } else { js_str!("-") };
 
         // 10. Let paddedYear be ToZeroPaddedDecimalString(abs(ℝ(yv)), 4).
         let yv = yv.unsigned_abs();
-        let padded_year = if yv >= 100_000 {
-            js_string!(&pad_six(yv))
+        let padded_year: JsString = if yv >= 100_000 {
+            pad_six(yv, &mut [0; 6]).into()
         } else if yv >= 10000 {
-            js_string!(&pad_five(yv))
+            pad_five(yv, &mut [0; 5]).into()
         } else {
-            js_string!(&pad_four(yv))
+            pad_four(yv, &mut [0; 4]).into()
         };
 
         // 11. Return the string-concatenation of
@@ -1692,15 +1700,15 @@ impl Date {
         // and TimeString(tv).
         Ok(JsValue::from(js_string!(
             weekday,
-            utf16!(","),
-            utf16!(" "),
-            &day,
-            utf16!(" "),
+            js_str!(","),
+            js_str!(" "),
+            day,
+            js_str!(" "),
             month,
-            utf16!(" "),
+            js_str!(" "),
             year_sign,
             &padded_year,
-            utf16!(" "),
+            js_str!(" "),
             &time_string(tv)
         )))
     }
@@ -1755,12 +1763,10 @@ impl Date {
         let try_first = match hint.as_string() {
             // 3. If hint is "string" or "default", then
             // a. Let tryFirst be string.
-            Some(string) if string == utf16!("string") || string == utf16!("default") => {
-                PreferredType::String
-            }
+            Some(string) if string == "string" || string == "default" => PreferredType::String,
             // 4. Else if hint is "number", then
             // a. Let tryFirst be number.
-            Some(number) if number == utf16!("number") => PreferredType::Number,
+            Some(number) if number == "number" => PreferredType::Number,
             // 5. Else, throw a TypeError exception.
             _ => {
                 return Err(JsNativeError::typ()

core/engine/src/builtins/date/tests.rs

@@ -1,4 +1,5 @@
 use crate::{js_string, run_test_actions, JsNativeErrorKind, TestAction};
+use boa_macros::js_str;
 use indoc::indoc;
 use time::{macros::format_description, util::local_offset, OffsetDateTime};
 
@@ -787,7 +788,7 @@ fn date_proto_set_utc_seconds() {
 fn date_proto_to_date_string() {
     run_test_actions([TestAction::assert_eq(
         "new Date(2020, 6, 8, 9, 16, 15, 779).toDateString()",
-        js_string!("Wed Jul 08 2020"),
+        js_str!("Wed Jul 08 2020"),
     )]);
 }
 
@@ -795,7 +796,7 @@ fn date_proto_to_date_string() {
 fn date_proto_to_gmt_string() {
     run_test_actions([TestAction::assert_eq(
         "new Date(Date.UTC(2020, 6, 8, 9, 16, 15, 779)).toGMTString()",
-        js_string!("Wed, 08 Jul 2020 09:16:15 GMT"),
+        js_str!("Wed, 08 Jul 2020 09:16:15 GMT"),
     )]);
 }
 
@@ -803,7 +804,7 @@ fn date_proto_to_gmt_string() {
 fn date_proto_to_iso_string() {
     run_test_actions([TestAction::assert_eq(
         "new Date(Date.UTC(2020, 6, 8, 9, 16, 15, 779)).toISOString()",
-        js_string!("2020-07-08T09:16:15.779Z"),
+        js_str!("2020-07-08T09:16:15.779Z"),
     )]);
 }
 
@@ -811,7 +812,7 @@ fn date_proto_to_iso_string() {
 fn date_proto_to_json() {
     run_test_actions([TestAction::assert_eq(
         "new Date(Date.UTC(2020, 6, 8, 9, 16, 15, 779)).toJSON()",
-        js_string!("2020-07-08T09:16:15.779Z"),
+        js_str!("2020-07-08T09:16:15.779Z"),
     )]);
 }
 
@@ -849,7 +850,7 @@ fn date_proto_to_time_string() {
 fn date_proto_to_utc_string() {
     run_test_actions([TestAction::assert_eq(
         "new Date(Date.UTC(2020, 6, 8, 9, 16, 15, 779)).toUTCString()",
-        js_string!("Wed, 08 Jul 2020 09:16:15 GMT"),
+        js_str!("Wed, 08 Jul 2020 09:16:15 GMT"),
     )]);
 }
 

core/engine/src/builtins/date/utils.rs

@@ -1,5 +1,5 @@
-use crate::{context::HostHooks, js_string, value::IntegerOrInfinity, JsString};
-use boa_macros::utf16;
+use crate::{context::HostHooks, js_string, value::IntegerOrInfinity, JsStr, JsString};
+use boa_macros::js_str;
 use std::{iter::Peekable, str::Chars};
 use time::{macros::format_description, OffsetDateTime, PrimitiveDateTime};
 
@@ -498,13 +498,16 @@ pub(crate) fn time_clip(time: f64) -> f64 {
 /// [spec]: https://tc39.es/ecma262/#sec-timestring
 pub(super) fn time_string(tv: f64) -> JsString {
     // 1. Let hour be ToZeroPaddedDecimalString(ℝ(HourFromTime(tv)), 2).
-    let hour = pad_two(hour_from_time(tv));
+    let mut binding = [0; 2];
+    let hour = pad_two(hour_from_time(tv), &mut binding);
 
     // 2. Let minute be ToZeroPaddedDecimalString(ℝ(MinFromTime(tv)), 2).
-    let minute = pad_two(min_from_time(tv));
+    let mut binding = [0; 2];
+    let minute = pad_two(min_from_time(tv), &mut binding);
 
-    // 3. Let second be ToZeroPaddedDecimalString(ℝ(SecFromTime(tv)), 2).
-    let second = pad_two(sec_from_time(tv));
+    // 3. Let second be ToZeroPaddedDecimalStringbindingFromTime(tv)), 2).
+    let mut binding = [0; 2];
+    let second = pad_two(sec_from_time(tv), &mut binding);
 
     // 4. Return the string-concatenation of
     //  hour,
@@ -515,12 +518,12 @@ pub(super) fn time_string(tv: f64) -> JsString {
     //  the code unit 0x0020 (SPACE),
     //  and "GMT".
     js_string!(
-        &hour,
-        utf16!(":"),
-        &minute,
-        utf16!(":"),
-        &second,
-        utf16!(" GMT")
+        hour,
+        js_str!(":"),
+        minute,
+        js_str!(":"),
+        second,
+        js_str!(" GMT")
     )
 }
 
@@ -533,50 +536,51 @@ pub(super) fn time_string(tv: f64) -> JsString {
 pub(super) fn date_string(tv: f64) -> JsString {
     // 1. Let weekday be the Name of the entry in Table 63 with the Number WeekDay(tv).
     let weekday = match week_day(tv) {
-        0 => utf16!("Sun"),
-        1 => utf16!("Mon"),
-        2 => utf16!("Tue"),
-        3 => utf16!("Wed"),
-        4 => utf16!("Thu"),
-        5 => utf16!("Fri"),
-        6 => utf16!("Sat"),
+        0 => js_str!("Sun"),
+        1 => js_str!("Mon"),
+        2 => js_str!("Tue"),
+        3 => js_str!("Wed"),
+        4 => js_str!("Thu"),
+        5 => js_str!("Fri"),
+        6 => js_str!("Sat"),
         _ => unreachable!(),
     };
 
     // 2. Let month be the Name of the entry in Table 64 with the Number MonthFromTime(tv).
     let month = match month_from_time(tv) {
-        0 => utf16!("Jan"),
-        1 => utf16!("Feb"),
-        2 => utf16!("Mar"),
-        3 => utf16!("Apr"),
-        4 => utf16!("May"),
-        5 => utf16!("Jun"),
-        6 => utf16!("Jul"),
-        7 => utf16!("Aug"),
-        8 => utf16!("Sep"),
-        9 => utf16!("Oct"),
-        10 => utf16!("Nov"),
-        11 => utf16!("Dec"),
+        0 => js_str!("Jan"),
+        1 => js_str!("Feb"),
+        2 => js_str!("Mar"),
+        3 => js_str!("Apr"),
+        4 => js_str!("May"),
+        5 => js_str!("Jun"),
+        6 => js_str!("Jul"),
+        7 => js_str!("Aug"),
+        8 => js_str!("Sep"),
+        9 => js_str!("Oct"),
+        10 => js_str!("Nov"),
+        11 => js_str!("Dec"),
         _ => unreachable!(),
     };
 
     // 3. Let day be ToZeroPaddedDecimalString(ℝ(DateFromTime(tv)), 2).
-    let day = pad_two(date_from_time(tv));
+    let mut binding = [0; 2];
+    let day = pad_two(date_from_time(tv), &mut binding);
 
     // 4. Let yv be YearFromTime(tv).
     let yv = year_from_time(tv);
 
     // 5. If yv is +0𝔽 or yv > +0𝔽, let yearSign be the empty String; otherwise, let yearSign be "-".
-    let year_sign = if yv >= 0 { utf16!("") } else { utf16!("-") };
+    let year_sign = if yv >= 0 { js_str!("") } else { js_str!("-") };
 
     // 6. Let paddedYear be ToZeroPaddedDecimalString(abs(ℝ(yv)), 4).
     let yv = yv.unsigned_abs();
-    let padded_year = if yv >= 100_000 {
-        js_string!(&pad_six(yv))
+    let padded_year: JsString = if yv >= 100_000 {
+        pad_six(yv, &mut [0; 6]).into()
     } else if yv >= 10000 {
-        js_string!(&pad_five(yv))
+        pad_five(yv, &mut [0; 5]).into()
     } else {
-        js_string!(&pad_four(yv))
+        pad_four(yv, &mut [0; 4]).into()
     };
 
     // 7. Return the string-concatenation of
@@ -590,11 +594,11 @@ pub(super) fn date_string(tv: f64) -> JsString {
     // and paddedYear.
     js_string!(
         weekday,
-        utf16!(" "),
+        js_str!(" "),
         month,
-        utf16!(" "),
-        &day,
-        utf16!(" "),
+        js_str!(" "),
+        day,
+        js_str!(" "),
         year_sign,
         &padded_year
     )
@@ -620,26 +624,28 @@ pub(super) fn time_zone_string(t: f64, hooks: &dyn HostHooks) -> JsString {
     let (offset_sign, abs_offset) = if offset >= 0.0 {
         // a. Let offsetSign be "+".
         // b. Let absOffset be offset.
-        (utf16!("+"), offset)
+        (js_str!("+"), offset)
     }
     // 6. Else,
     else {
         // a. Let offsetSign be "-".
         // b. Let absOffset be -offset.
-        (utf16!("-"), -offset)
+        (js_str!("-"), -offset)
     };
 
     // 7. Let offsetMin be ToZeroPaddedDecimalString(ℝ(MinFromTime(absOffset)), 2).
-    let offset_min = pad_two(min_from_time(abs_offset));
+    let mut binding = [0; 2];
+    let offset_min = pad_two(min_from_time(abs_offset), &mut binding);
 
     // 8. Let offsetHour be ToZeroPaddedDecimalString(ℝ(HourFromTime(absOffset)), 2).
-    let offset_hour = pad_two(hour_from_time(abs_offset));
+    let mut binding = [0; 2];
+    let offset_hour = pad_two(hour_from_time(abs_offset), &mut binding);
 
     // 9. Let tzName be an implementation-defined string that is either the empty String or the
     // string-concatenation of the code unit 0x0020 (SPACE), the code unit 0x0028 (LEFT PARENTHESIS),
     // an implementation-defined timezone name, and the code unit 0x0029 (RIGHT PARENTHESIS).
     // 10. Return the string-concatenation of offsetSign, offsetHour, offsetMin, and tzName.
-    js_string!(offset_sign, &offset_hour, &offset_min)
+    js_string!(offset_sign, offset_hour, offset_min)
 }
 
 /// Abstract operation `ToDateString ( tv )`
@@ -651,7 +657,7 @@ pub(super) fn time_zone_string(t: f64, hooks: &dyn HostHooks) -> JsString {
 pub(super) fn to_date_string_t(tv: f64, hooks: &dyn HostHooks) -> JsString {
     // 1. If tv is NaN, return "Invalid Date".
     if tv.is_nan() {
-        return JsString::from("Invalid Date");
+        return js_string!("Invalid Date");
     }
 
     // 2. Let t be LocalTime(tv).
@@ -664,7 +670,7 @@ pub(super) fn to_date_string_t(tv: f64, hooks: &dyn HostHooks) -> JsString {
     // and TimeZoneString(tv).
     js_string!(
         &date_string(t),
-        utf16!(" "),
+        js_str!(" "),
         &time_string(t),
         &time_zone_string(t, hooks)
     )
@@ -676,46 +682,61 @@ fn local_timezone_offset_seconds(t: f64, hooks: &dyn HostHooks) -> i32 {
     hooks.local_timezone_offset_seconds(seconds)
 }
 
-pub(super) fn pad_two(t: u8) -> [u16; 2] {
-    if t < 10 {
-        [0x30, 0x30 + u16::from(t)]
+pub(super) fn pad_two(t: u8, output: &mut [u8; 2]) -> JsStr<'_> {
+    *output = if t < 10 {
+        [b'0', b'0' + t]
     } else {
-        [0x30 + (u16::from(t) / 10), 0x30 + (u16::from(t) % 10)]
-    }
+        [b'0' + (t / 10), b'0' + (t % 10)]
+    };
+    debug_assert!(output.is_ascii());
+
+    JsStr::latin1(output)
 }
 
-pub(super) fn pad_three(t: u16) -> [u16; 3] {
-    [0x30 + t / 100, 0x30 + ((t / 10) % 10), 0x30 + (t % 10)]
+pub(super) fn pad_three(t: u16, output: &mut [u8; 3]) -> JsStr<'_> {
+    *output = [
+        b'0' + (t / 100) as u8,
+        b'0' + ((t / 10) % 10) as u8,
+        b'0' + (t % 10) as u8,
+    ];
+
+    JsStr::latin1(output)
 }
 
-pub(super) fn pad_four(t: u32) -> [u16; 4] {
-    [
-        0x30 + (t / 1000) as u16,
-        0x30 + ((t / 100) % 10) as u16,
-        0x30 + ((t / 10) % 10) as u16,
-        0x30 + (t % 10) as u16,
-    ]
+pub(super) fn pad_four(t: u32, output: &mut [u8; 4]) -> JsStr<'_> {
+    *output = [
+        b'0' + (t / 1000) as u8,
+        b'0' + ((t / 100) % 10) as u8,
+        b'0' + ((t / 10) % 10) as u8,
+        b'0' + (t % 10) as u8,
+    ];
+
+    JsStr::latin1(output)
 }
 
-pub(super) fn pad_five(t: u32) -> [u16; 5] {
-    [
-        0x30 + (t / 10_000) as u16,
-        0x30 + ((t / 1000) % 10) as u16,
-        0x30 + ((t / 100) % 10) as u16,
-        0x30 + ((t / 10) % 10) as u16,
-        0x30 + (t % 10) as u16,
-    ]
+pub(super) fn pad_five(t: u32, output: &mut [u8; 5]) -> JsStr<'_> {
+    *output = [
+        b'0' + (t / 10_000) as u8,
+        b'0' + ((t / 1000) % 10) as u8,
+        b'0' + ((t / 100) % 10) as u8,
+        b'0' + ((t / 10) % 10) as u8,
+        b'0' + (t % 10) as u8,
+    ];
+
+    JsStr::latin1(output)
 }
 
-pub(super) fn pad_six(t: u32) -> [u16; 6] {
-    [
-        0x30 + (t / 100_000) as u16,
-        0x30 + ((t / 10_000) % 10) as u16,
-        0x30 + ((t / 1000) % 10) as u16,
-        0x30 + ((t / 100) % 10) as u16,
-        0x30 + ((t / 10) % 10) as u16,
-        0x30 + (t % 10) as u16,
-    ]
+pub(super) fn pad_six(t: u32, output: &mut [u8; 6]) -> JsStr<'_> {
+    *output = [
+        b'0' + (t / 100_000) as u8,
+        b'0' + ((t / 10_000) % 10) as u8,
+        b'0' + ((t / 1000) % 10) as u8,
+        b'0' + ((t / 100) % 10) as u8,
+        b'0' + ((t / 10) % 10) as u8,
+        b'0' + (t % 10) as u8,
+    ];
+
+    JsStr::latin1(output)
 }
 
 /// Parse a date string according to the steps specified in [`Date.parse`][spec].

core/engine/src/builtins/error/aggregate.rs

@@ -17,9 +17,10 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::{Attribute, PropertyDescriptorBuilder},
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsResult, JsString, JsValue,
 };
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 use super::{Error, ErrorObject};
@@ -35,8 +36,8 @@ impl IntrinsicObject for AggregateError {
         BuiltInBuilder::from_standard_constructor::<Self>(realm)
             .prototype(realm.intrinsics().constructors().error().constructor())
             .inherits(Some(realm.intrinsics().constructors().error().prototype()))
-            .property(utf16!("name"), Self::NAME, attribute)
-            .property(utf16!("message"), js_string!(), attribute)
+            .property(js_str!("name"), Self::NAME, attribute)
+            .property(js_str!("message"), js_string!(), attribute)
             .build();
     }
 
@@ -95,7 +96,7 @@ impl BuiltInConstructor for AggregateError {
             let msg = message.to_string(context)?;
 
             // b. Perform CreateNonEnumerableDataPropertyOrThrow(O, "message", msg).
-            o.create_non_enumerable_data_property_or_throw(utf16!("message"), msg, context);
+            o.create_non_enumerable_data_property_or_throw(js_str!("message"), msg, context);
         }
 
         // 4. Perform ? InstallErrorCause(O, options).
@@ -112,7 +113,7 @@ impl BuiltInConstructor for AggregateError {
         //      [[Value]]: CreateArrayFromList(errorsList)
         //    }).
         o.define_property_or_throw(
-            utf16!("errors"),
+            js_str!("errors"),
             PropertyDescriptorBuilder::new()
                 .configurable(true)
                 .enumerable(false)

core/engine/src/builtins/error/eval.rs

@@ -18,9 +18,10 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsResult, JsString, JsValue,
 };
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 use super::{Error, ErrorObject};
@@ -37,8 +38,8 @@ impl IntrinsicObject for EvalError {
         BuiltInBuilder::from_standard_constructor::<Self>(realm)
             .prototype(realm.intrinsics().constructors().error().constructor())
             .inherits(Some(realm.intrinsics().constructors().error().prototype()))
-            .property(utf16!("name"), Self::NAME, attribute)
-            .property(utf16!("message"), js_string!(), attribute)
+            .property(js_str!("name"), Self::NAME, attribute)
+            .property(js_str!("message"), js_string!(), attribute)
             .build();
     }
 
@@ -94,7 +95,7 @@ impl BuiltInConstructor for EvalError {
             let msg = message.to_string(context)?;
 
             // b. Perform CreateNonEnumerableDataPropertyOrThrow(O, "message", msg).
-            o.create_non_enumerable_data_property_or_throw(utf16!("message"), msg, context);
+            o.create_non_enumerable_data_property_or_throw(js_str!("message"), msg, context);
         }
 
         // 4. Perform ? InstallErrorCause(O, options).

core/engine/src/builtins/error/mod.rs

@@ -18,10 +18,11 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsData, JsResult, JsString, JsValue,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 pub(crate) mod aggregate;
@@ -136,8 +137,8 @@ impl IntrinsicObject for Error {
 
         let attribute = Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE;
         BuiltInBuilder::from_standard_constructor::<Self>(realm)
-            .property(utf16!("name"), Self::NAME, attribute)
-            .property(utf16!("message"), js_string!(), attribute)
+            .property(js_string!("name"), Self::NAME, attribute)
+            .property(js_string!("message"), js_string!(), attribute)
             .method(Self::to_string, js_string!("toString"), 0)
             .build();
     }
@@ -191,7 +192,7 @@ impl BuiltInConstructor for Error {
             let msg = message.to_string(context)?;
 
             // b. Perform CreateNonEnumerableDataPropertyOrThrow(O, "message", msg).
-            o.create_non_enumerable_data_property_or_throw(utf16!("message"), msg, context);
+            o.create_non_enumerable_data_property_or_throw(js_string!("message"), msg, context);
         }
 
         // 4. Perform ? InstallErrorCause(O, options).
@@ -210,12 +211,12 @@ impl Error {
     ) -> JsResult<()> {
         // 1. If Type(options) is Object and ? HasProperty(options, "cause") is true, then
         if let Some(options) = options.as_object() {
-            if options.has_property(utf16!("cause"), context)? {
+            if options.has_property(js_str!("cause"), context)? {
                 // a. Let cause be ? Get(options, "cause").
-                let cause = options.get(utf16!("cause"), context)?;
+                let cause = options.get(js_str!("cause"), context)?;
 
                 // b. Perform CreateNonEnumerableDataPropertyOrThrow(O, "cause", cause).
-                o.create_non_enumerable_data_property_or_throw(utf16!("cause"), cause, context);
+                o.create_non_enumerable_data_property_or_throw(js_str!("cause"), cause, context);
             }
         }
 
@@ -246,7 +247,7 @@ impl Error {
             .ok_or_else(|| JsNativeError::typ().with_message("'this' is not an Object"))?;
 
         // 3. Let name be ? Get(O, "name").
-        let name = o.get(js_string!("name"), context)?;
+        let name = o.get(js_str!("name"), context)?;
 
         // 4. If name is undefined, set name to "Error"; otherwise set name to ? ToString(name).
         let name = if name.is_undefined() {
@@ -256,7 +257,7 @@ impl Error {
         };
 
         // 5. Let msg be ? Get(O, "message").
-        let msg = o.get(js_string!("message"), context)?;
+        let msg = o.get(js_str!("message"), context)?;
 
         // 6. If msg is undefined, set msg to the empty String; otherwise set msg to ? ToString(msg).
         let msg = if msg.is_undefined() {
@@ -277,6 +278,6 @@ impl Error {
 
         // 9. Return the string-concatenation of name, the code unit 0x003A (COLON),
         // the code unit 0x0020 (SPACE), and msg.
-        Ok(js_string!(&name, utf16!(": "), &msg).into())
+        Ok(js_string!(&name, js_str!(": "), &msg).into())
     }
 }

core/engine/src/builtins/error/range.rs

@@ -16,9 +16,10 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsResult, JsString, JsValue,
 };
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 use super::{Error, ErrorObject};
@@ -35,8 +36,8 @@ impl IntrinsicObject for RangeError {
         BuiltInBuilder::from_standard_constructor::<Self>(realm)
             .prototype(realm.intrinsics().constructors().error().constructor())
             .inherits(Some(realm.intrinsics().constructors().error().prototype()))
-            .property(utf16!("name"), Self::NAME, attribute)
-            .property(utf16!("message"), js_string!(), attribute)
+            .property(js_str!("name"), Self::NAME, attribute)
+            .property(js_str!("message"), js_string!(), attribute)
             .build();
     }
 
@@ -92,7 +93,7 @@ impl BuiltInConstructor for RangeError {
             let msg = message.to_string(context)?;
 
             // b. Perform CreateNonEnumerableDataPropertyOrThrow(O, "message", msg).
-            o.create_non_enumerable_data_property_or_throw(utf16!("message"), msg, context);
+            o.create_non_enumerable_data_property_or_throw(js_str!("message"), msg, context);
         }
 
         // 4. Perform ? InstallErrorCause(O, options).

core/engine/src/builtins/error/reference.rs

@@ -16,9 +16,10 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsResult, JsString, JsValue,
 };
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 use super::{Error, ErrorObject};
@@ -34,8 +35,8 @@ impl IntrinsicObject for ReferenceError {
         BuiltInBuilder::from_standard_constructor::<Self>(realm)
             .prototype(realm.intrinsics().constructors().error().constructor())
             .inherits(Some(realm.intrinsics().constructors().error().prototype()))
-            .property(js_string!("name"), Self::NAME, attribute)
-            .property(js_string!("message"), js_string!(), attribute)
+            .property(js_str!("name"), Self::NAME, attribute)
+            .property(js_str!("message"), js_string!(), attribute)
             .build();
     }
 
@@ -94,7 +95,7 @@ impl BuiltInConstructor for ReferenceError {
             let msg = message.to_string(context)?;
 
             // b. Perform CreateNonEnumerableDataPropertyOrThrow(O, "message", msg).
-            o.create_non_enumerable_data_property_or_throw(utf16!("message"), msg, context);
+            o.create_non_enumerable_data_property_or_throw(js_str!("message"), msg, context);
         }
 
         // 4. Perform ? InstallErrorCause(O, options).

core/engine/src/builtins/error/syntax.rs

@@ -18,9 +18,10 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsResult, JsString, JsValue,
 };
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 use super::{Error, ErrorObject};
@@ -37,8 +38,8 @@ impl IntrinsicObject for SyntaxError {
         BuiltInBuilder::from_standard_constructor::<Self>(realm)
             .prototype(realm.intrinsics().constructors().error().constructor())
             .inherits(Some(realm.intrinsics().constructors().error().prototype()))
-            .property(utf16!("name"), Self::NAME, attribute)
-            .property(utf16!("message"), js_string!(), attribute)
+            .property(js_str!("name"), Self::NAME, attribute)
+            .property(js_str!("message"), js_string!(), attribute)
             .build();
     }
 
@@ -97,7 +98,7 @@ impl BuiltInConstructor for SyntaxError {
             let msg = message.to_string(context)?;
 
             // b. Perform CreateNonEnumerableDataPropertyOrThrow(O, "message", msg).
-            o.create_non_enumerable_data_property_or_throw(utf16!("message"), msg, context);
+            o.create_non_enumerable_data_property_or_throw(js_str!("message"), msg, context);
         }
 
         // 4. Perform ? InstallErrorCause(O, options).

core/engine/src/builtins/error/tests.rs

@@ -1,42 +1,34 @@
-use crate::{js_string, run_test_actions, TestAction};
+use crate::{run_test_actions, TestAction};
+use boa_macros::js_str;
 use indoc::indoc;
 
 #[test]
 fn error_to_string() {
     run_test_actions([
-        TestAction::assert_eq("(new Error('1')).toString()", js_string!("Error: 1")),
-        TestAction::assert_eq(
-            "(new RangeError('2')).toString()",
-            js_string!("RangeError: 2"),
-        ),
+        TestAction::assert_eq("(new Error('1')).toString()", js_str!("Error: 1")),
+        TestAction::assert_eq("(new RangeError('2')).toString()", js_str!("RangeError: 2")),
         TestAction::assert_eq(
             "(new ReferenceError('3')).toString()",
-            js_string!("ReferenceError: 3"),
+            js_str!("ReferenceError: 3"),
         ),
         TestAction::assert_eq(
             "(new SyntaxError('4')).toString()",
-            js_string!("SyntaxError: 4"),
-        ),
-        TestAction::assert_eq(
-            "(new TypeError('5')).toString()",
-            js_string!("TypeError: 5"),
-        ),
-        TestAction::assert_eq(
-            "(new EvalError('6')).toString()",
-            js_string!("EvalError: 6"),
+            js_str!("SyntaxError: 4"),
         ),
-        TestAction::assert_eq("(new URIError('7')).toString()", js_string!("URIError: 7")),
+        TestAction::assert_eq("(new TypeError('5')).toString()", js_str!("TypeError: 5")),
+        TestAction::assert_eq("(new EvalError('6')).toString()", js_str!("EvalError: 6")),
+        TestAction::assert_eq("(new URIError('7')).toString()", js_str!("URIError: 7")),
         // no message
-        TestAction::assert_eq("(new Error()).toString()", js_string!("Error")),
-        TestAction::assert_eq("(new RangeError()).toString()", js_string!("RangeError")),
+        TestAction::assert_eq("(new Error()).toString()", js_str!("Error")),
+        TestAction::assert_eq("(new RangeError()).toString()", js_str!("RangeError")),
         TestAction::assert_eq(
             "(new ReferenceError()).toString()",
-            js_string!("ReferenceError"),
+            js_str!("ReferenceError"),
         ),
-        TestAction::assert_eq("(new SyntaxError()).toString()", js_string!("SyntaxError")),
-        TestAction::assert_eq("(new TypeError()).toString()", js_string!("TypeError")),
-        TestAction::assert_eq("(new EvalError()).toString()", js_string!("EvalError")),
-        TestAction::assert_eq("(new URIError()).toString()", js_string!("URIError")),
+        TestAction::assert_eq("(new SyntaxError()).toString()", js_str!("SyntaxError")),
+        TestAction::assert_eq("(new TypeError()).toString()", js_str!("TypeError")),
+        TestAction::assert_eq("(new EvalError()).toString()", js_str!("EvalError")),
+        TestAction::assert_eq("(new URIError()).toString()", js_str!("URIError")),
         // no name
         TestAction::assert_eq(
             indoc! {r#"
@@ -44,7 +36,7 @@ fn error_to_string() {
                 message.name = '';
                 message.toString()
             "#},
-            js_string!("message"),
+            js_str!("message"),
         ),
     ]);
 }
@@ -52,14 +44,14 @@ fn error_to_string() {
 #[test]
 fn error_names() {
     run_test_actions([
-        TestAction::assert_eq("Error.name", js_string!("Error")),
-        TestAction::assert_eq("EvalError.name", js_string!("EvalError")),
-        TestAction::assert_eq("RangeError.name", js_string!("RangeError")),
-        TestAction::assert_eq("ReferenceError.name", js_string!("ReferenceError")),
-        TestAction::assert_eq("SyntaxError.name", js_string!("SyntaxError")),
-        TestAction::assert_eq("URIError.name", js_string!("URIError")),
-        TestAction::assert_eq("TypeError.name", js_string!("TypeError")),
-        TestAction::assert_eq("AggregateError.name", js_string!("AggregateError")),
+        TestAction::assert_eq("Error.name", js_str!("Error")),
+        TestAction::assert_eq("EvalError.name", js_str!("EvalError")),
+        TestAction::assert_eq("RangeError.name", js_str!("RangeError")),
+        TestAction::assert_eq("ReferenceError.name", js_str!("ReferenceError")),
+        TestAction::assert_eq("SyntaxError.name", js_str!("SyntaxError")),
+        TestAction::assert_eq("URIError.name", js_str!("URIError")),
+        TestAction::assert_eq("TypeError.name", js_str!("TypeError")),
+        TestAction::assert_eq("AggregateError.name", js_str!("AggregateError")),
     ]);
 }
 

core/engine/src/builtins/error/type.rs

@@ -24,9 +24,10 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsResult, JsString, JsValue, NativeFunction,
 };
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 use super::{Error, ErrorObject};
@@ -43,8 +44,8 @@ impl IntrinsicObject for TypeError {
         BuiltInBuilder::from_standard_constructor::<Self>(realm)
             .prototype(realm.intrinsics().constructors().error().constructor())
             .inherits(Some(realm.intrinsics().constructors().error().prototype()))
-            .property(utf16!("name"), Self::NAME, attribute)
-            .property(utf16!("message"), js_string!(), attribute)
+            .property(js_str!("name"), Self::NAME, attribute)
+            .property(js_str!("message"), js_string!(), attribute)
             .build();
     }
 
@@ -100,7 +101,7 @@ impl BuiltInConstructor for TypeError {
             let msg = message.to_string(context)?;
 
             // b. Perform CreateNonEnumerableDataPropertyOrThrow(O, "message", msg).
-            o.create_non_enumerable_data_property_or_throw(utf16!("message"), msg, context);
+            o.create_non_enumerable_data_property_or_throw(js_str!("message"), msg, context);
         }
 
         // 4. Perform ? InstallErrorCause(O, options).
@@ -119,7 +120,7 @@ impl IntrinsicObject for ThrowTypeError {
         let obj = BuiltInBuilder::with_intrinsic::<Self>(realm)
             .prototype(realm.intrinsics().constructors().function().prototype())
             .static_property(StaticJsStrings::LENGTH, 0, Attribute::empty())
-            .static_property(utf16!("name"), js_string!(), Attribute::empty())
+            .static_property(js_str!("name"), js_string!(), Attribute::empty())
             .build();
 
         let mut obj = obj.borrow_mut();

core/engine/src/builtins/error/uri.rs

@@ -17,9 +17,10 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsResult, JsString, JsValue,
 };
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 use super::{Error, ErrorObject};
@@ -36,8 +37,8 @@ impl IntrinsicObject for UriError {
         BuiltInBuilder::from_standard_constructor::<Self>(realm)
             .prototype(realm.intrinsics().constructors().error().constructor())
             .inherits(Some(realm.intrinsics().constructors().error().prototype()))
-            .property(utf16!("name"), Self::NAME, attribute)
-            .property(utf16!("message"), js_string!(), attribute)
+            .property(js_str!("name"), Self::NAME, attribute)
+            .property(js_str!("message"), js_string!(), attribute)
             .build();
     }
 
@@ -93,7 +94,7 @@ impl BuiltInConstructor for UriError {
             let msg = message.to_string(context)?;
 
             // b. Perform CreateNonEnumerableDataPropertyOrThrow(O, "message", msg).
-            o.create_non_enumerable_data_property_or_throw(utf16!("message"), msg, context);
+            o.create_non_enumerable_data_property_or_throw(js_str!("message"), msg, context);
         }
 
         // 4. Perform ? InstallErrorCause(O, options).

core/engine/src/builtins/escape/mod.rs

@@ -59,7 +59,7 @@ fn escape(_: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsVa
     // 5. Let k be 0.
     // 6. Repeat, while k < len,
     //     a. Let C be the code unit at index k within string.
-    for &cp in &*string {
+    for cp in &string {
         // b. If unescapedSet contains C, then
         if is_unescaped(cp) {
             // i. Let S be C.
@@ -86,7 +86,7 @@ fn escape(_: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsVa
     }
 
     // 7. Return R.
-    Ok(js_string!(vec).into())
+    Ok(js_string!(&vec[..]).into())
 }
 
 /// The `unescape` function
@@ -124,7 +124,7 @@ fn unescape(_: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<Js
     // 3. Let R be the empty String.
     let mut vec = Vec::with_capacity(string.len());
 
-    let mut codepoints = <PeekableN<_, 6>>::new(string.iter().copied());
+    let mut codepoints = <PeekableN<_, 6>>::new(string.iter());
 
     // 2. Let len be the length of string.
     // 4. Let k be 0.
@@ -192,7 +192,7 @@ fn unescape(_: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<Js
         vec.push(unescaped_cp);
     }
     // 6. Return R.
-    Ok(js_string!(vec).into())
+    Ok(js_string!(&vec[..]).into())
 }
 
 /// An iterator that can peek `N` items.

core/engine/src/builtins/eval/mod.rs

@@ -122,7 +122,8 @@ impl Eval {
         //     b. If script is a List of errors, throw a SyntaxError exception.
         //     c. If script Contains ScriptBody is false, return undefined.
         //     d. Let body be the ScriptBody of script.
-        let mut parser = Parser::new(Source::from_utf16(x));
+        let x = x.to_vec();
+        let mut parser = Parser::new(Source::from_utf16(&x));
         parser.set_identifier(context.next_parser_identifier());
         if strict {
             parser.set_strict();

core/engine/src/builtins/function/mod.rs

@@ -21,18 +21,20 @@ use crate::{
     error::JsNativeError,
     js_string,
     native_function::NativeFunctionObject,
-    object::{internal_methods::get_prototype_from_constructor, JsObject},
     object::{
-        internal_methods::{CallValue, InternalObjectMethods, ORDINARY_INTERNAL_METHODS},
-        JsData, JsFunction, PrivateElement, PrivateName,
+        internal_methods::{
+            get_prototype_from_constructor, CallValue, InternalObjectMethods,
+            ORDINARY_INTERNAL_METHODS,
+        },
+        JsData, JsFunction, JsObject, PrivateElement, PrivateName,
     },
     property::{Attribute, PropertyDescriptor, PropertyKey},
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     symbol::JsSymbol,
     value::IntegerOrInfinity,
     vm::{ActiveRunnable, CallFrame, CallFrameFlags, CodeBlock},
-    Context, JsArgs, JsResult, JsString, JsValue,
+    Context, JsArgs, JsResult, JsStr, JsString, JsValue,
 };
 use boa_ast::{
     function::{FormalParameterList, FunctionBody},
@@ -43,6 +45,7 @@ use boa_ast::{
 };
 use boa_gc::{self, custom_trace, Finalize, Gc, Trace};
 use boa_interner::Sym;
+use boa_macros::js_str;
 use boa_parser::{Parser, Source};
 use boa_profiler::Profiler;
 use thin_vec::ThinVec;
@@ -312,13 +315,13 @@ impl IntrinsicObject for BuiltInFunctionObject {
             .method(Self::to_string, js_string!("toString"), 0)
             .property(JsSymbol::has_instance(), has_instance, Attribute::default())
             .accessor(
-                utf16!("caller"),
+                js_string!("caller"),
                 Some(throw_type_error.clone()),
                 Some(throw_type_error.clone()),
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("arguments"),
+                js_string!("arguments"),
                 Some(throw_type_error.clone()),
                 Some(throw_type_error),
                 Attribute::CONFIGURABLE,
@@ -473,7 +476,15 @@ impl BuiltInFunctionObject {
             //         i. Let nextArgString be parameterStrings[k].
             //         ii. Set P to the string-concatenation of P, "," (a comma), and nextArgString.
             //         iii. Set k to k + 1.
-            let parameters = param_list.join(utf16!(","));
+
+            // TODO: Replace with standard `Iterator::intersperse` iterator method when it's stabilized.
+            //       See: <https://github.com/rust-lang/rust/issues/79524>
+            let parameters = itertools::Itertools::intersperse(
+                param_list.iter().map(JsString::iter),
+                js_str!(",").iter(),
+            )
+            .flatten()
+            .collect::<Vec<_>>();
             let mut parser = Parser::new(Source::from_utf16(&parameters));
             parser.set_identifier(context.next_parser_identifier());
 
@@ -518,7 +529,7 @@ impl BuiltInFunctionObject {
             // 14. Let bodyParseString be the string-concatenation of 0x000A (LINE FEED), bodyString, and 0x000A (LINE FEED).
             let mut body_parse = Vec::with_capacity(body.len());
             body_parse.push(u16::from(b'\n'));
-            body_parse.extend_from_slice(&body);
+            body_parse.extend(body.iter());
             body_parse.push(u16::from(b'\n'));
 
             // 19. Let body be ParseText(StringToCodePoints(bodyParseString), bodySym).
@@ -743,7 +754,7 @@ impl BuiltInFunctionObject {
         .expect("defining the `length` property for a new object should not fail");
 
         // 8. Let targetName be ? Get(Target, "name").
-        let target_name = target.get(utf16!("name"), context)?;
+        let target_name = target.get(js_str!("name"), context)?;
 
         // 9. If Type(targetName) is not String, set targetName to the empty String.
         let target_name = target_name
@@ -751,7 +762,7 @@ impl BuiltInFunctionObject {
             .map_or_else(JsString::default, Clone::clone);
 
         // 10. Perform SetFunctionName(F, targetName, "bound").
-        set_function_name(&f, &target_name.into(), Some(js_string!("bound")), context);
+        set_function_name(&f, &target_name.into(), Some(js_str!("bound")), context);
 
         // 11. Return F.
         Ok(f.into())
@@ -816,7 +827,7 @@ impl BuiltInFunctionObject {
             let name = {
                 // Is there a case here where if there is no name field on a value
                 // name should default to None? Do all functions have names set?
-                let value = object.get(utf16!("name"), &mut *context)?;
+                let value = object.get(js_str!("name"), &mut *context)?;
                 if value.is_null_or_undefined() {
                     js_string!()
                 } else {
@@ -824,10 +835,10 @@ impl BuiltInFunctionObject {
                 }
             };
             return Ok(
-                js_string!(utf16!("function "), &name, utf16!("() { [native code] }")).into(),
+                js_string!(js_str!("function "), &name, js_str!("() { [native code] }")).into(),
             );
         } else if object_borrow.is::<Proxy>() || object_borrow.is::<BoundFunction>() {
-            return Ok(js_string!(utf16!("function () { [native code] }")).into());
+            return Ok(js_string!("function () { [native code] }").into());
         }
 
         let function = object_borrow
@@ -837,9 +848,9 @@ impl BuiltInFunctionObject {
         let code = function.codeblock();
 
         Ok(js_string!(
-            utf16!("function "),
+            js_str!("function "),
             code.name(),
-            utf16!("() { [native code] }")
+            js_str!("() { [native code] }")
         )
         .into())
     }
@@ -871,7 +882,7 @@ impl BuiltInFunctionObject {
 pub(crate) fn set_function_name(
     function: &JsObject,
     name: &PropertyKey,
-    prefix: Option<JsString>,
+    prefix: Option<JsStr<'_>>,
     context: &mut Context,
 ) {
     // 1. Assert: F is an extensible object that does not have a "name" own property.
@@ -883,7 +894,7 @@ pub(crate) fn set_function_name(
             // c. Else, set name to the string-concatenation of "[", description, and "]".
             sym.description().map_or_else(
                 || js_string!(),
-                |desc| js_string!(utf16!("["), &desc, utf16!("]")),
+                |desc| js_string!(js_str!("["), &desc, js_str!("]")),
             )
         }
         PropertyKey::String(string) => string.clone(),
@@ -900,7 +911,7 @@ pub(crate) fn set_function_name(
 
     // 5. If prefix is present, then
     if let Some(prefix) = prefix {
-        name = js_string!(&prefix, utf16!(" "), &name);
+        name = js_string!(prefix, js_str!(" "), &name);
         // b. If F has an [[InitialName]] internal slot, then
         // i. Optionally, set F.[[InitialName]] to name.
         // todo: implement [[InitialName]] for builtins
@@ -910,7 +921,7 @@ pub(crate) fn set_function_name(
     // [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }).
     function
         .define_property_or_throw(
-            utf16!("name"),
+            js_str!("name"),
             PropertyDescriptor::builder()
                 .value(name)
                 .writable(false)

core/engine/src/builtins/function/tests.rs

@@ -6,6 +6,7 @@ use crate::{
     property::{Attribute, PropertyDescriptor},
     run_test_actions, JsNativeErrorKind, JsValue, TestAction,
 };
+use boa_macros::js_str;
 use indoc::indoc;
 
 #[allow(clippy::float_cmp)]
@@ -69,7 +70,7 @@ fn function_prototype() {
 fn function_prototype_call() {
     run_test_actions([TestAction::assert_eq(
         "Object.prototype.toString.call(new Error())",
-        js_string!("[object Error]"),
+        js_str!("[object Error]"),
     )]);
 }
 
@@ -168,13 +169,13 @@ fn closure_capture_clone() {
                     (string, object),
                 ),
             )
-            .name("closure")
+            .name(js_str!("closure"))
             .build();
 
-            ctx.register_global_property(js_string!("closure"), func, Attribute::default())
+            ctx.register_global_property(js_str!("closure"), func, Attribute::default())
                 .unwrap();
         }),
-        TestAction::assert_eq("closure()", js_string!("Hello world!")),
+        TestAction::assert_eq("closure()", js_str!("Hello world!")),
     ]);
 }
 

core/engine/src/builtins/intl/collator/mod.rs

@@ -1,4 +1,5 @@
 use boa_gc::{custom_trace, Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use icu_collator::{
     provider::CollationMetadataV1Marker, AlternateHandling, CaseFirst, Collator as NativeCollator,
@@ -28,7 +29,7 @@ use crate::{
     },
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     symbol::JsSymbol,
     Context, JsArgs, JsData, JsNativeError, JsResult, JsString, JsValue,
 };
@@ -241,28 +242,28 @@ impl BuiltInConstructor for Collator {
         //     a. Let localeData be %Collator%.[[SortLocaleData]].
         // 6. Else,
         //     a. Let localeData be %Collator%.[[SearchLocaleData]].
-        let usage = get_option(&options, utf16!("usage"), context)?.unwrap_or_default();
+        let usage = get_option(&options, js_str!("usage"), context)?.unwrap_or_default();
 
         // 7. Let opt be a new Record.
         // 8. Let matcher be ? GetOption(options, "localeMatcher", string, « "lookup", "best fit" », "best fit").
         // 9. Set opt.[[localeMatcher]] to matcher.
-        let matcher = get_option(&options, utf16!("localeMatcher"), context)?.unwrap_or_default();
+        let matcher = get_option(&options, js_str!("localeMatcher"), context)?.unwrap_or_default();
 
         // 10. Let collation be ? GetOption(options, "collation", string, empty, undefined).
         // 11. If collation is not undefined, then
         //     a. If collation does not match the Unicode Locale Identifier type nonterminal, throw a RangeError exception.
         // 12. Set opt.[[co]] to collation.
-        let collation = get_option(&options, utf16!("collation"), context)?;
+        let collation = get_option(&options, js_str!("collation"), context)?;
 
         // 13. Let numeric be ? GetOption(options, "numeric", boolean, empty, undefined).
         // 14. If numeric is not undefined, then
         //     a. Let numeric be ! ToString(numeric).
         // 15. Set opt.[[kn]] to numeric.
-        let numeric = get_option(&options, utf16!("numeric"), context)?;
+        let numeric = get_option(&options, js_str!("numeric"), context)?;
 
         // 16. Let caseFirst be ? GetOption(options, "caseFirst", string, « "upper", "lower", "false" », undefined).
         // 17. Set opt.[[kf]] to caseFirst.
-        let case_first = get_option(&options, utf16!("caseFirst"), context)?;
+        let case_first = get_option(&options, js_str!("caseFirst"), context)?;
 
         let mut intl_options = IntlOptions {
             matcher,
@@ -314,7 +315,7 @@ impl BuiltInConstructor for Collator {
 
         // 26. Let sensitivity be ? GetOption(options, "sensitivity", string, « "base", "accent", "case", "variant" », undefined).
         // 28. Set collator.[[Sensitivity]] to sensitivity.
-        let sensitivity = get_option(&options, utf16!("sensitivity"), context)?
+        let sensitivity = get_option(&options, js_str!("sensitivity"), context)?
             // 27. If sensitivity is undefined, then
             //     a. If usage is "sort", then
             //         i. Let sensitivity be "variant".
@@ -327,7 +328,7 @@ impl BuiltInConstructor for Collator {
         // 29. Let ignorePunctuation be ? GetOption(options, "ignorePunctuation", boolean, empty, false).
         // 30. Set collator.[[IgnorePunctuation]] to ignorePunctuation.
         let ignore_punctuation: bool =
-            get_option(&options, utf16!("ignorePunctuation"), context)?.unwrap_or_default();
+            get_option(&options, js_str!("ignorePunctuation"), context)?.unwrap_or_default();
 
         let (strength, case_level) = sensitivity.map(Sensitivity::to_collator_options).unzip();
 
@@ -442,13 +443,22 @@ impl Collator {
 
                         // 3. If x is not provided, let x be undefined.
                         // 5. Let X be ? ToString(x).
-                        let x = args.get_or_undefined(0).to_string(context)?;
+                        let x = args
+                            .get_or_undefined(0)
+                            .to_string(context)?
+                            .iter()
+                            .collect::<Vec<_>>();
 
                         // 4. If y is not provided, let y be undefined.
                         // 6. Let Y be ? ToString(y).
-                        let y = args.get_or_undefined(1).to_string(context)?;
+                        let y = args
+                            .get_or_undefined(1)
+                            .to_string(context)?
+                            .iter()
+                            .collect::<Vec<_>>();
 
                         // 7. Return CompareStrings(collator, X, Y).
+
                         let result = collator.collator.compare_utf16(&x, &y) as i32;
 
                         Ok(result.into())
@@ -507,58 +517,58 @@ impl Collator {
         // 5. Return options.
         options
             .create_data_property_or_throw(
-                utf16!("locale"),
+                js_str!("locale"),
                 js_string!(collator.locale.to_string()),
                 context,
             )
             .expect("operation must not fail per the spec");
         options
             .create_data_property_or_throw(
-                utf16!("usage"),
+                js_str!("usage"),
                 match collator.usage {
-                    Usage::Search => js_string!("search"),
-                    Usage::Sort => js_string!("sort"),
+                    Usage::Search => js_str!("search"),
+                    Usage::Sort => js_str!("sort"),
                 },
                 context,
             )
             .expect("operation must not fail per the spec");
         options
             .create_data_property_or_throw(
-                utf16!("sensitivity"),
+                js_str!("sensitivity"),
                 match collator.sensitivity {
-                    Sensitivity::Base => js_string!("base"),
-                    Sensitivity::Accent => js_string!("accent"),
-                    Sensitivity::Case => js_string!("case"),
-                    Sensitivity::Variant => js_string!("variant"),
+                    Sensitivity::Base => js_str!("base"),
+                    Sensitivity::Accent => js_str!("accent"),
+                    Sensitivity::Case => js_str!("case"),
+                    Sensitivity::Variant => js_str!("variant"),
                 },
                 context,
             )
             .expect("operation must not fail per the spec");
         options
             .create_data_property_or_throw(
-                js_string!("ignorePunctuation"),
+                js_str!("ignorePunctuation"),
                 collator.ignore_punctuation,
                 context,
             )
             .expect("operation must not fail per the spec");
         options
             .create_data_property_or_throw(
-                js_string!("collation"),
+                js_str!("collation"),
                 js_string!(collator.collation.to_string()),
                 context,
             )
             .expect("operation must not fail per the spec");
         options
-            .create_data_property_or_throw(utf16!("numeric"), collator.numeric, context)
+            .create_data_property_or_throw(js_str!("numeric"), collator.numeric, context)
             .expect("operation must not fail per the spec");
         if let Some(kf) = collator.case_first {
             options
                 .create_data_property_or_throw(
-                    js_string!("caseFirst"),
+                    js_str!("caseFirst"),
                     match kf {
-                        CaseFirst::Off => js_string!("false"),
-                        CaseFirst::LowerFirst => js_string!("lower"),
-                        CaseFirst::UpperFirst => js_string!("upper"),
+                        CaseFirst::Off => js_str!("false"),
+                        CaseFirst::LowerFirst => js_str!("lower"),
+                        CaseFirst::UpperFirst => js_str!("upper"),
                         _ => unreachable!(),
                     },
                     context,

core/engine/src/builtins/intl/date_time_format.rs

@@ -17,11 +17,12 @@ use crate::{
     js_string,
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsData, JsResult, JsString, JsValue,
 };
 
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use icu_datetime::options::preferences::HourCycle;
 
@@ -205,10 +206,10 @@ pub(crate) fn to_date_time_options(
     if [DateTimeReqs::Date, DateTimeReqs::AnyAll].contains(required) {
         // a. For each property name prop of « "weekday", "year", "month", "day" », do
         for property in [
-            utf16!("weekday"),
-            utf16!("year"),
-            utf16!("month"),
-            utf16!("day"),
+            js_str!("weekday"),
+            js_str!("year"),
+            js_str!("month"),
+            js_str!("day"),
         ] {
             // i. Let value be ? Get(options, prop).
             let value = options.get(property, context)?;
@@ -225,11 +226,11 @@ pub(crate) fn to_date_time_options(
         // a. For each property name prop of « "dayPeriod", "hour", "minute", "second",
         // "fractionalSecondDigits" », do
         for property in [
-            utf16!("dayPeriod"),
-            utf16!("hour"),
-            utf16!("minute"),
-            utf16!("second"),
-            utf16!("fractionalSecondDigits"),
+            js_str!("dayPeriod"),
+            js_str!("hour"),
+            js_str!("minute"),
+            js_str!("second"),
+            js_str!("fractionalSecondDigits"),
         ] {
             // i. Let value be ? Get(options, prop).
             let value = options.get(property, context)?;
@@ -242,10 +243,10 @@ pub(crate) fn to_date_time_options(
     }
 
     // 6. Let dateStyle be ? Get(options, "dateStyle").
-    let date_style = options.get(utf16!("dateStyle"), context)?;
+    let date_style = options.get(js_str!("dateStyle"), context)?;
 
     // 7. Let timeStyle be ? Get(options, "timeStyle").
-    let time_style = options.get(utf16!("timeStyle"), context)?;
+    let time_style = options.get(js_str!("timeStyle"), context)?;
 
     // 8. If dateStyle is not undefined or timeStyle is not undefined, let needDefaults be false.
     if !date_style.is_undefined() || !time_style.is_undefined() {
@@ -271,18 +272,18 @@ pub(crate) fn to_date_time_options(
     // 11. If needDefaults is true and defaults is either "date" or "all", then
     if need_defaults && [DateTimeReqs::Date, DateTimeReqs::AnyAll].contains(defaults) {
         // a. For each property name prop of « "year", "month", "day" », do
-        for property in [utf16!("year"), utf16!("month"), utf16!("day")] {
+        for property in [js_str!("year"), js_str!("month"), js_str!("day")] {
             // i. Perform ? CreateDataPropertyOrThrow(options, prop, "numeric").
-            options.create_data_property_or_throw(property, js_string!("numeric"), context)?;
+            options.create_data_property_or_throw(property, js_str!("numeric"), context)?;
         }
     }
 
     // 12. If needDefaults is true and defaults is either "time" or "all", then
     if need_defaults && [DateTimeReqs::Time, DateTimeReqs::AnyAll].contains(defaults) {
         // a. For each property name prop of « "hour", "minute", "second" », do
-        for property in [utf16!("hour"), utf16!("minute"), utf16!("second")] {
+        for property in [js_str!("hour"), js_str!("minute"), js_str!("second")] {
             // i. Perform ? CreateDataPropertyOrThrow(options, prop, "numeric").
-            options.create_data_property_or_throw(property, js_string!("numeric"), context)?;
+            options.create_data_property_or_throw(property, js_str!("numeric"), context)?;
         }
     }
 

core/engine/src/builtins/intl/list_format/mod.rs

@@ -1,6 +1,7 @@
 use std::fmt::Write;
 
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use icu_list::{provider::AndListV1Marker, ListFormatter, ListLength};
 use icu_locid::Locale;
@@ -16,7 +17,7 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     symbol::JsSymbol,
     Context, JsArgs, JsData, JsNativeError, JsResult, JsString, JsValue,
 };
@@ -114,7 +115,7 @@ impl BuiltInConstructor for ListFormat {
 
         // 5. Let opt be a new Record.
         // 6. Let matcher be ? GetOption(options, "localeMatcher", string, « "lookup", "best fit" », "best fit").
-        let matcher = get_option(&options, utf16!("localeMatcher"), context)?.unwrap_or_default();
+        let matcher = get_option(&options, js_str!("localeMatcher"), context)?.unwrap_or_default();
 
         // 7. Set opt.[[localeMatcher]] to matcher.
         // 8. Let localeData be %ListFormat%.[[LocaleData]].
@@ -131,11 +132,11 @@ impl BuiltInConstructor for ListFormat {
 
         // 11. Let type be ? GetOption(options, "type", string, « "conjunction", "disjunction", "unit" », "conjunction").
         // 12. Set listFormat.[[Type]] to type.
-        let typ = get_option(&options, utf16!("type"), context)?.unwrap_or_default();
+        let typ = get_option(&options, js_str!("type"), context)?.unwrap_or_default();
 
         // 13. Let style be ? GetOption(options, "style", string, « "long", "short", "narrow" », "long").
         // 14. Set listFormat.[[Style]] to style.
-        let style = get_option(&options, utf16!("style"), context)?.unwrap_or(ListLength::Wide);
+        let style = get_option(&options, js_str!("style"), context)?.unwrap_or(ListLength::Wide);
 
         // 15. Let dataLocale be r.[[dataLocale]].
         // 16. Let dataLocaleData be localeData.[[<dataLocale>]].
@@ -380,11 +381,11 @@ impl ListFormat {
                 .create(OrdinaryObject, vec![]);
 
             // b. Perform ! CreateDataPropertyOrThrow(O, "type", part.[[Type]]).
-            o.create_data_property_or_throw(utf16!("type"), js_string!(part.typ()), context)
+            o.create_data_property_or_throw(js_str!("type"), js_string!(part.typ()), context)
                 .expect("operation must not fail per the spec");
 
             // c. Perform ! CreateDataPropertyOrThrow(O, "value", part.[[Value]]).
-            o.create_data_property_or_throw(utf16!("value"), js_string!(part.value()), context)
+            o.create_data_property_or_throw(js_str!("value"), js_string!(part.value()), context)
                 .expect("operation must not fail per the spec");
 
             // d. Perform ! CreateDataPropertyOrThrow(result, ! ToString(n), O).
@@ -435,29 +436,29 @@ impl ListFormat {
         //     d. Perform ! CreateDataPropertyOrThrow(options, p, v).
         options
             .create_data_property_or_throw(
-                utf16!("locale"),
+                js_str!("locale"),
                 js_string!(lf.locale.to_string()),
                 context,
             )
             .expect("operation must not fail per the spec");
         options
             .create_data_property_or_throw(
-                js_string!("type"),
+                js_str!("type"),
                 match lf.typ {
-                    ListFormatType::Conjunction => js_string!("conjunction"),
-                    ListFormatType::Disjunction => js_string!("disjunction"),
-                    ListFormatType::Unit => js_string!("unit"),
+                    ListFormatType::Conjunction => js_str!("conjunction"),
+                    ListFormatType::Disjunction => js_str!("disjunction"),
+                    ListFormatType::Unit => js_str!("unit"),
                 },
                 context,
             )
             .expect("operation must not fail per the spec");
         options
             .create_data_property_or_throw(
-                js_string!("style"),
+                js_str!("style"),
                 match lf.style {
-                    ListLength::Wide => js_string!("long"),
-                    ListLength::Short => js_string!("short"),
-                    ListLength::Narrow => js_string!("narrow"),
+                    ListLength::Wide => js_str!("long"),
+                    ListLength::Short => js_str!("short"),
+                    ListLength::Narrow => js_str!("narrow"),
                     _ => unreachable!(),
                 },
                 context,

core/engine/src/builtins/intl/locale/mod.rs

@@ -1,8 +1,5 @@
-use crate::{
-    builtins::options::get_option,
-    realm::Realm,
-    string::{common::StaticJsStrings, utf16},
-};
+use crate::{builtins::options::get_option, realm::Realm, string::common::StaticJsStrings};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use icu_collator::CaseFirst;
 use icu_datetime::options::preferences::HourCycle;
@@ -236,17 +233,17 @@ impl BuiltInConstructor for Locale {
             // 4. Let language be ? GetOption(options, "language", string, empty, undefined).
             // 5. If language is not undefined, then
             //    a. If language does not match the unicode_language_subtag production, throw a RangeError exception.
-            let language = get_option(options, utf16!("language"), context)?;
+            let language = get_option(options, js_str!("language"), context)?;
 
             // 6. Let script be ? GetOption(options, "script", string, empty, undefined).
             // 7. If script is not undefined, then
             //    a. If script does not match the unicode_script_subtag production, throw a RangeError exception.
-            let script = get_option(options, utf16!("script"), context)?;
+            let script = get_option(options, js_str!("script"), context)?;
 
             // 8. Let region be ? GetOption(options, "region", string, empty, undefined).
             // 9. If region is not undefined, then
             //    a. If region does not match the unicode_region_subtag production, throw a RangeError exception.
-            let region = get_option(options, utf16!("region"), context)?;
+            let region = get_option(options, js_str!("region"), context)?;
 
             // 10. Set tag to ! CanonicalizeUnicodeLocaleId(tag).
             context
@@ -294,17 +291,17 @@ impl BuiltInConstructor for Locale {
         // 14. If calendar is not undefined, then
         // 15. Set opt.[[ca]] to calendar.
         //     a. If calendar does not match the Unicode Locale Identifier type nonterminal, throw a RangeError exception.
-        let ca = get_option(options, utf16!("calendar"), context)?;
+        let ca = get_option(options, js_str!("calendar"), context)?;
 
         // 16. Let collation be ? GetOption(options, "collation", string, empty, undefined).
         // 17. If collation is not undefined, then
         // 18. Set opt.[[co]] to collation.
         //     a. If collation does not match the Unicode Locale Identifier type nonterminal, throw a RangeError exception.
-        let co = get_option(options, utf16!("collation"), context)?;
+        let co = get_option(options, js_str!("collation"), context)?;
 
         // 19. Let hc be ? GetOption(options, "hourCycle", string, « "h11", "h12", "h23", "h24" », undefined).
         // 20. Set opt.[[hc]] to hc.
-        let hc = get_option(options, utf16!("hourCycle"), context)?.map(|hc| match hc {
+        let hc = get_option(options, js_str!("hourCycle"), context)?.map(|hc| match hc {
             HourCycle::H24 => value!("h24"),
             HourCycle::H23 => value!("h23"),
             HourCycle::H12 => value!("h12"),
@@ -313,7 +310,7 @@ impl BuiltInConstructor for Locale {
 
         // 21. Let kf be ? GetOption(options, "caseFirst", string, « "upper", "lower", "false" », undefined).
         // 22. Set opt.[[kf]] to kf.
-        let kf = get_option(options, utf16!("caseFirst"), context)?.map(|kf| match kf {
+        let kf = get_option(options, js_str!("caseFirst"), context)?.map(|kf| match kf {
             CaseFirst::UpperFirst => value!("upper"),
             CaseFirst::LowerFirst => value!("lower"),
             CaseFirst::Off => value!("false"),
@@ -323,7 +320,7 @@ impl BuiltInConstructor for Locale {
         // 23. Let kn be ? GetOption(options, "numeric", boolean, empty, undefined).
         // 24. If kn is not undefined, set kn to ! ToString(kn).
         // 25. Set opt.[[kn]] to kn.
-        let kn = get_option(options, utf16!("numeric"), context)?.map(|b| {
+        let kn = get_option(options, js_str!("numeric"), context)?.map(|b| {
             if b {
                 value!("true")
             } else {
@@ -335,7 +332,7 @@ impl BuiltInConstructor for Locale {
         // 27. If numberingSystem is not undefined, then
         // 28. Set opt.[[nu]] to numberingSystem.
         //     a. If numberingSystem does not match the Unicode Locale Identifier type nonterminal, throw a RangeError exception.
-        let nu = get_option(options, utf16!("numberingSystem"), context)?;
+        let nu = get_option(options, js_str!("numberingSystem"), context)?;
 
         // 29. Let r be ! ApplyUnicodeExtensionToTag(tag, opt, relevantExtensionKeys).
         // 30. Set locale.[[Locale]] to r.[[locale]].

core/engine/src/builtins/intl/locale/utils.rs

@@ -10,10 +10,10 @@ use crate::{
     context::icu::IntlProvider,
     js_string,
     object::JsObject,
-    string::utf16,
     Context, JsNativeError, JsResult, JsValue,
 };
 
+use boa_macros::js_str;
 use icu_collator::provider::CollationMetadataV1Marker;
 use icu_locid::{
     extensions::unicode::{Key, Value},
@@ -551,7 +551,7 @@ where
     let options = coerce_options_to_object(options, context)?;
 
     // 2. Let matcher be ? GetOption(options, "localeMatcher", string, « "lookup", "best fit" », "best fit").
-    let matcher = get_option(&options, utf16!("localeMatcher"), context)?.unwrap_or_default();
+    let matcher = get_option(&options, js_str!("localeMatcher"), context)?.unwrap_or_default();
 
     let elements = match matcher {
         // 4. Else,

core/engine/src/builtins/intl/number_format/mod.rs

@@ -1,7 +1,7 @@
 use std::borrow::Cow;
 
 use boa_gc::{Finalize, Trace};
-use boa_macros::utf16;
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use fixed_decimal::{FixedDecimal, FloatPrecision, SignDisplay};
 use icu_decimal::{
@@ -221,13 +221,13 @@ impl BuiltInConstructor for NumberFormat {
 
         // 4. Let matcher be ? GetOption(options, "localeMatcher", string, « "lookup", "best fit" », "best fit").
         // 5. Set opt.[[localeMatcher]] to matcher.
-        let matcher = get_option(&options, utf16!("localeMatcher"), context)?.unwrap_or_default();
+        let matcher = get_option(&options, js_str!("localeMatcher"), context)?.unwrap_or_default();
 
         // 6. Let numberingSystem be ? GetOption(options, "numberingSystem", string, empty, undefined).
         // 7. If numberingSystem is not undefined, then
         //     a. If numberingSystem cannot be matched by the type Unicode locale nonterminal, throw a RangeError exception.
         // 8. Set opt.[[nu]] to numberingSystem.
-        let numbering_system = get_option(&options, utf16!("numberingSystem"), context)?;
+        let numbering_system = get_option(&options, js_str!("numberingSystem"), context)?;
 
         let mut intl_options = IntlOptions {
             matcher,
@@ -277,7 +277,7 @@ impl BuiltInConstructor for NumberFormat {
 
         // 18. Let notation be ? GetOption(options, "notation", string, « "standard", "scientific", "engineering", "compact" », "standard").
         // 19. Set numberFormat.[[Notation]] to notation.
-        let notation = get_option(&options, utf16!("notation"), context)?.unwrap_or_default();
+        let notation = get_option(&options, js_str!("notation"), context)?.unwrap_or_default();
 
         // 20. Perform ? SetNumberFormatDigitOptions(numberFormat, options, mnfdDefault, mxfdDefault, notation).
         let digit_options = DigitFormatOptions::from_options(
@@ -290,7 +290,7 @@ impl BuiltInConstructor for NumberFormat {
 
         // 21. Let compactDisplay be ? GetOption(options, "compactDisplay", string, « "short", "long" », "short").
         let compact_display =
-            get_option(&options, utf16!("compactDisplay"), context)?.unwrap_or_default();
+            get_option(&options, js_str!("compactDisplay"), context)?.unwrap_or_default();
 
         // 22. Let defaultUseGrouping be "auto".
         let mut default_use_grouping = GroupingStrategy::Auto;
@@ -325,7 +325,7 @@ impl BuiltInConstructor for NumberFormat {
             // <https://tc39.es/ecma402/#sec-getbooleanorstringnumberformatoption>
 
             // 1. Let value be ? Get(options, property).
-            let value = options.get(utf16!("useGrouping"), context)?;
+            let value = options.get(js_str!("useGrouping"), context)?;
 
             // 2. If value is undefined, return fallback.
             if value.is_undefined() {
@@ -363,7 +363,7 @@ impl BuiltInConstructor for NumberFormat {
         // 29. Let signDisplay be ? GetOption(options, "signDisplay", string, « "auto", "never", "always", "exceptZero", "negative" », "auto").
         // 30. Set numberFormat.[[SignDisplay]] to signDisplay.
         let sign_display =
-            get_option(&options, utf16!("signDisplay"), context)?.unwrap_or(SignDisplay::Auto);
+            get_option(&options, js_str!("signDisplay"), context)?.unwrap_or(SignDisplay::Auto);
 
         let formatter = FixedDecimalFormatter::try_new_unstable(
             context.intl_provider(),

core/engine/src/builtins/intl/number_format/options.rs

@@ -2,7 +2,7 @@ use std::fmt;
 
 use fixed_decimal::{FixedDecimal, FloatPrecision, RoundingIncrement as BaseMultiple, SignDisplay};
 
-use boa_macros::utf16;
+use boa_macros::js_str;
 use tinystr::TinyAsciiStr;
 
 use crate::{
@@ -10,7 +10,7 @@ use crate::{
         intl::options::{default_number_option, get_number_option},
         options::{get_option, OptionType, ParsableOptionType, RoundingMode},
     },
-    js_string, Context, JsNativeError, JsObject, JsResult, JsString,
+    js_string, Context, JsNativeError, JsObject, JsResult, JsStr, JsString,
 };
 
 #[derive(Debug, Copy, Clone, Default, Eq, PartialEq)]
@@ -245,9 +245,9 @@ impl ParsableOptionType for Currency {}
 #[derive(Debug, Eq, PartialEq)]
 pub(crate) struct Unit {
     // INVARIANT: `numerator` must only contain ASCII lowercase alphabetic letters or `-`.
-    numerator: &'static str,
+    numerator: JsStr<'static>,
     // INVARIANT: if `denominator` is not empty, it must only contain ASCII lowercase alphabetic letters or `-`
-    denominator: &'static str,
+    denominator: JsStr<'static>,
 }
 
 impl Unit {
@@ -258,9 +258,7 @@ impl Unit {
         } else {
             // TODO: this is not optimal for now, but the new JS strings should
             // allow us to optimize this to simple casts from ASCII to JsString.
-            let numerator: Vec<u16> = self.numerator.encode_utf16().collect();
-            let denominator: Vec<u16> = self.denominator.encode_utf16().collect();
-            js_string!(&numerator, utf16!("-per-"), &denominator)
+            js_string!(self.numerator, js_str!("-per-"), self.denominator)
         }
     }
 }
@@ -281,7 +279,7 @@ impl std::str::FromStr for Unit {
     ///
     /// [spec]: https://tc39.es/ecma402/#sec-iswellformedunitidentifier
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        static SANCTIONED_UNITS: [&str; 45] = [
+        const SANCTIONED_UNITS: [&str; 45] = [
             "acre",
             "bit",
             "byte",
@@ -339,13 +337,17 @@ impl std::str::FromStr for Unit {
             .map(|i| SANCTIONED_UNITS[i])
             .map_err(|_| ParseUnitError)?;
 
+        let num = JsStr::latin1(num.as_bytes());
+
         let den = if den.is_empty() {
-            ""
+            JsStr::EMPTY
         } else {
-            SANCTIONED_UNITS
+            let value = SANCTIONED_UNITS
                 .binary_search(&den)
                 .map(|i| SANCTIONED_UNITS[i])
-                .map_err(|_| ParseUnitError)?
+                .map_err(|_| ParseUnitError)?;
+
+            JsStr::latin1(value.as_bytes())
         };
 
         Ok(Self {
@@ -390,12 +392,12 @@ impl UnitFormatOptions {
     pub(crate) fn from_options(options: &JsObject, context: &mut Context) -> JsResult<Self> {
         // 1. Let style be ? GetOption(options, "style", string, « "decimal", "percent", "currency", "unit" », "decimal").
         // 2. Set intlObj.[[Style]] to style.
-        let style: Style = get_option(options, utf16!("style"), context)?.unwrap_or_default();
+        let style: Style = get_option(options, js_str!("style"), context)?.unwrap_or_default();
 
         // 3. Let currency be ? GetOption(options, "currency", string, empty, undefined).
         // 5. Else,
         //     a. If IsWellFormedCurrencyCode(currency) is false, throw a RangeError exception.
-        let currency = get_option(options, utf16!("currency"), context)?;
+        let currency = get_option(options, js_str!("currency"), context)?;
 
         // 4. If currency is undefined, then
         if currency.is_none() {
@@ -411,16 +413,16 @@ impl UnitFormatOptions {
 
         // 6. Let currencyDisplay be ? GetOption(options, "currencyDisplay", string, « "code", "symbol", "narrowSymbol", "name" », "symbol").
         let currency_display =
-            get_option(options, utf16!("currencyDisplay"), context)?.unwrap_or_default();
+            get_option(options, js_str!("currencyDisplay"), context)?.unwrap_or_default();
 
         // 7. Let currencySign be ? GetOption(options, "currencySign", string, « "standard", "accounting" », "standard").
         let currency_sign =
-            get_option(options, utf16!("currencySign"), context)?.unwrap_or_default();
+            get_option(options, js_str!("currencySign"), context)?.unwrap_or_default();
 
         // 8. Let unit be ? GetOption(options, "unit", string, empty, undefined).
         // 10. Else,
         //     a. If IsWellFormedUnitIdentifier(unit) is false, throw a RangeError exception.
-        let unit = get_option(options, utf16!("unit"), context)?;
+        let unit = get_option(options, js_str!("unit"), context)?;
         // 9. If unit is undefined, then
         if unit.is_none() {
             // a. If style is "unit", throw a TypeError exception.
@@ -434,7 +436,8 @@ impl UnitFormatOptions {
         }
 
         // 11. Let unitDisplay be ? GetOption(options, "unitDisplay", string, « "short", "narrow", "long" », "short").
-        let unit_display = get_option(options, utf16!("unitDisplay"), context)?.unwrap_or_default();
+        let unit_display =
+            get_option(options, js_str!("unitDisplay"), context)?.unwrap_or_default();
 
         // 14. Return unused.
         Ok(match style {
@@ -489,25 +492,26 @@ impl DigitFormatOptions {
     ) -> JsResult<Self> {
         // 1. Let mnid be ? GetNumberOption(options, "minimumIntegerDigits,", 1, 21, 1).
         let minimum_integer_digits =
-            get_number_option(options, utf16!("minimumIntegerDigits"), 1, 21, context)?
+            get_number_option(options, js_str!("minimumIntegerDigits"), 1, 21, context)?
                 .unwrap_or(1);
         // 2. Let mnfd be ? Get(options, "minimumFractionDigits").
-        let min_float_digits = options.get(utf16!("minimumFractionDigits"), context)?;
+        let min_float_digits = options.get(js_str!("minimumFractionDigits"), context)?;
         // 3. Let mxfd be ? Get(options, "maximumFractionDigits").
-        let max_float_digits = options.get(utf16!("maximumFractionDigits"), context)?;
+        let max_float_digits = options.get(js_str!("maximumFractionDigits"), context)?;
         // 4. Let mnsd be ? Get(options, "minimumSignificantDigits").
-        let min_sig_digits = options.get(utf16!("minimumSignificantDigits"), context)?;
+        let min_sig_digits = options.get(js_str!("minimumSignificantDigits"), context)?;
         // 5. Let mxsd be ? Get(options, "maximumSignificantDigits").
-        let max_sig_digits = options.get(utf16!("maximumSignificantDigits"), context)?;
+        let max_sig_digits = options.get(js_str!("maximumSignificantDigits"), context)?;
 
         // 7. Let roundingPriority be ? GetOption(options, "roundingPriority", string, « "auto", "morePrecision", "lessPrecision" », "auto").
         let mut rounding_priority =
-            get_option(options, utf16!("roundingPriority"), context)?.unwrap_or_default();
+            get_option(options, js_str!("roundingPriority"), context)?.unwrap_or_default();
 
         // 8. Let roundingIncrement be ? GetNumberOption(options, "roundingIncrement", 1, 5000, 1).
         // 9. If roundingIncrement is not in « 1, 2, 5, 10, 20, 25, 50, 100, 200, 250, 500, 1000, 2000, 2500, 5000 », throw a RangeError exception.
         let rounding_increment =
-            get_number_option(options, utf16!("roundingIncrement"), 1, 5000, context)?.unwrap_or(1);
+            get_number_option(options, js_str!("roundingIncrement"), 1, 5000, context)?
+                .unwrap_or(1);
 
         let rounding_increment =
             RoundingIncrement::from_u16(rounding_increment).ok_or_else(|| {
@@ -516,11 +520,11 @@ impl DigitFormatOptions {
 
         // 10. Let roundingMode be ? GetOption(options, "roundingMode", string, « "ceil", "floor", "expand", "trunc", "halfCeil", "halfFloor", "halfExpand", "halfTrunc", "halfEven" », "halfExpand").
         let rounding_mode =
-            get_option(options, utf16!("roundingMode"), context)?.unwrap_or_default();
+            get_option(options, js_str!("roundingMode"), context)?.unwrap_or_default();
 
         // 11. Let trailingZeroDisplay be ? GetOption(options, "trailingZeroDisplay", string, « "auto", "stripIfInteger" », "auto").
         let trailing_zero_display =
-            get_option(options, utf16!("trailingZeroDisplay"), context)?.unwrap_or_default();
+            get_option(options, js_str!("trailingZeroDisplay"), context)?.unwrap_or_default();
 
         // 12. NOTE: All fields required by SetNumberFormatDigitOptions have now been read from options. The remainder of this AO interprets the options and may throw exceptions.
 

core/engine/src/builtins/intl/options.rs

@@ -5,7 +5,7 @@ use num_traits::FromPrimitive;
 use crate::{
     builtins::{options::ParsableOptionType, OrdinaryObject},
     object::JsObject,
-    Context, JsNativeError, JsResult, JsValue,
+    Context, JsNativeError, JsResult, JsStr, JsValue,
 };
 
 /// `IntlOptions` aggregates the `locale_matcher` selector and any other object
@@ -60,7 +60,7 @@ impl ParsableOptionType for LocaleMatcher {}
 /// [spec]: https://tc39.es/ecma402/#sec-getnumberoption
 pub(super) fn get_number_option<T>(
     options: &JsObject,
-    property: &[u16],
+    property: JsStr<'_>,
     minimum: T,
     maximum: T,
     context: &mut Context,

core/engine/src/builtins/intl/plural_rules/mod.rs

@@ -1,7 +1,7 @@
 mod options;
 
 use boa_gc::{Finalize, Trace};
-use boa_macros::utf16;
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use fixed_decimal::FixedDecimal;
 use icu_locid::Locale;
@@ -22,7 +22,7 @@ use crate::{
     property::Attribute,
     realm::Realm,
     string::common::StaticJsStrings,
-    Context, JsArgs, JsData, JsNativeError, JsObject, JsResult, JsString, JsSymbol, JsValue,
+    Context, JsArgs, JsData, JsNativeError, JsObject, JsResult, JsStr, JsString, JsSymbol, JsValue,
 };
 
 use super::{
@@ -121,12 +121,12 @@ impl BuiltInConstructor for PluralRules {
         // 3. Let opt be a new Record.
         // 4. Let matcher be ? GetOption(options, "localeMatcher", string, « "lookup", "best fit" », "best fit").
         // 5. Set opt.[[localeMatcher]] to matcher.
-        let matcher = get_option(&options, utf16!("localeMatcher"), context)?.unwrap_or_default();
+        let matcher = get_option(&options, js_str!("localeMatcher"), context)?.unwrap_or_default();
 
         // 6. Let t be ? GetOption(options, "type", string, « "cardinal", "ordinal" », "cardinal").
         // 7. Set pluralRules.[[Type]] to t.
         let rule_type =
-            get_option(&options, utf16!("type"), context)?.unwrap_or(PluralRuleType::Cardinal);
+            get_option(&options, js_str!("type"), context)?.unwrap_or(PluralRuleType::Cardinal);
 
         // 8. Perform ? SetNumberFormatDigitOptions(pluralRules, options, +0𝔽, 3𝔽, "standard").
         let format_options =
@@ -330,21 +330,21 @@ impl PluralRules {
         let mut options = ObjectInitializer::new(context);
         options
             .property(
-                js_string!("locale"),
+                js_str!("locale"),
                 js_string!(plural_rules.locale.to_string()),
                 Attribute::all(),
             )
             .property(
-                js_string!("type"),
+                js_str!("type"),
                 match plural_rules.rule_type {
-                    PluralRuleType::Cardinal => js_string!("cardinal"),
-                    PluralRuleType::Ordinal => js_string!("ordinal"),
-                    _ => js_string!("unknown"),
+                    PluralRuleType::Cardinal => js_str!("cardinal"),
+                    PluralRuleType::Ordinal => js_str!("ordinal"),
+                    _ => js_str!("unknown"),
                 },
                 Attribute::all(),
             )
             .property(
-                js_string!("minimumIntegerDigits"),
+                js_str!("minimumIntegerDigits"),
                 plural_rules.format_options.minimum_integer_digits,
                 Attribute::all(),
             );
@@ -353,16 +353,8 @@ impl PluralRules {
             plural_rules.format_options.rounding_type.fraction_digits()
         {
             options
-                .property(
-                    js_string!("minimumFractionDigits"),
-                    minimum,
-                    Attribute::all(),
-                )
-                .property(
-                    js_string!("maximumFractionDigits"),
-                    maximum,
-                    Attribute::all(),
-                );
+                .property(js_str!("minimumFractionDigits"), minimum, Attribute::all())
+                .property(js_str!("maximumFractionDigits"), maximum, Attribute::all());
         }
 
         if let Some(Extrema { minimum, maximum }) = plural_rules
@@ -372,12 +364,12 @@ impl PluralRules {
         {
             options
                 .property(
-                    js_string!("minimumSignificantDigits"),
+                    js_str!("minimumSignificantDigits"),
                     minimum,
                     Attribute::all(),
                 )
                 .property(
-                    js_string!("maximumSignificantDigits"),
+                    js_str!("maximumSignificantDigits"),
                     maximum,
                     Attribute::all(),
                 );
@@ -385,17 +377,17 @@ impl PluralRules {
 
         options
             .property(
-                js_string!("roundingMode"),
+                js_str!("roundingMode"),
                 js_string!(plural_rules.format_options.rounding_mode.to_js_string()),
                 Attribute::all(),
             )
             .property(
-                js_string!("roundingIncrement"),
+                js_str!("roundingIncrement"),
                 plural_rules.format_options.rounding_increment.to_u16(),
                 Attribute::all(),
             )
             .property(
-                js_string!("trailingZeroDisplay"),
+                js_str!("trailingZeroDisplay"),
                 plural_rules
                     .format_options
                     .trailing_zero_display
@@ -416,7 +408,7 @@ impl PluralRules {
 
         // 6. Perform ! CreateDataProperty(options, "pluralCategories", CreateArrayFromList(pluralCategories)).
         options.property(
-            js_string!("pluralCategories"),
+            js_str!("pluralCategories"),
             plural_categories,
             Attribute::all(),
         );
@@ -428,7 +420,7 @@ impl PluralRules {
         // 9. Else,
         //     a. Perform ! CreateDataPropertyOrThrow(options, "roundingPriority", "auto").
         options.property(
-            js_string!("roundingPriority"),
+            js_str!("roundingPriority"),
             js_string!(plural_rules.format_options.rounding_priority.to_js_string()),
             Attribute::all(),
         );
@@ -480,13 +472,13 @@ fn resolve_plural(plural_rules: &PluralRules, n: f64) -> ResolvedPlural {
     }
 }
 
-fn plural_category_to_js_string(category: PluralCategory) -> JsString {
+fn plural_category_to_js_string(category: PluralCategory) -> JsStr<'static> {
     match category {
-        PluralCategory::Zero => js_string!("zero"),
-        PluralCategory::One => js_string!("one"),
-        PluralCategory::Two => js_string!("two"),
-        PluralCategory::Few => js_string!("few"),
-        PluralCategory::Many => js_string!("many"),
-        PluralCategory::Other => js_string!("other"),
+        PluralCategory::Zero => js_str!("zero"),
+        PluralCategory::One => js_str!("one"),
+        PluralCategory::Two => js_str!("two"),
+        PluralCategory::Few => js_str!("few"),
+        PluralCategory::Many => js_str!("many"),
+        PluralCategory::Other => js_str!("other"),
     }
 }

core/engine/src/builtins/intl/segmenter/iterator.rs

@@ -1,7 +1,9 @@
 use boa_gc::{Finalize, Trace};
 use boa_profiler::Profiler;
 use icu_segmenter::{
-    GraphemeClusterBreakIteratorUtf16, SentenceBreakIteratorUtf16, WordBreakIteratorUtf16,
+    GraphemeClusterBreakIteratorLatin1, GraphemeClusterBreakIteratorUtf16,
+    SentenceBreakIteratorLatin1, SentenceBreakIteratorUtf16, WordBreakIteratorLatin1,
+    WordBreakIteratorUtf16,
 };
 
 use crate::{
@@ -16,9 +18,12 @@ use crate::{
 use super::{create_segment_data_object, Segmenter};
 
 pub(crate) enum NativeSegmentIterator<'l, 's> {
-    Grapheme(GraphemeClusterBreakIteratorUtf16<'l, 's>),
-    Word(WordBreakIteratorUtf16<'l, 's>),
-    Sentence(SentenceBreakIteratorUtf16<'l, 's>),
+    GraphemeUtf16(GraphemeClusterBreakIteratorUtf16<'l, 's>),
+    WordUtf16(WordBreakIteratorUtf16<'l, 's>),
+    SentenceUtf16(SentenceBreakIteratorUtf16<'l, 's>),
+    GraphemeLatin1(GraphemeClusterBreakIteratorLatin1<'l, 's>),
+    WordLatin1(WordBreakIteratorLatin1<'l, 's>),
+    SentenceLatin1(SentenceBreakIteratorLatin1<'l, 's>),
 }
 
 impl Iterator for NativeSegmentIterator<'_, '_> {
@@ -26,9 +31,12 @@ impl Iterator for NativeSegmentIterator<'_, '_> {
 
     fn next(&mut self) -> Option<Self::Item> {
         match self {
-            NativeSegmentIterator::Grapheme(g) => g.next(),
-            NativeSegmentIterator::Word(w) => w.next(),
-            NativeSegmentIterator::Sentence(s) => s.next(),
+            NativeSegmentIterator::GraphemeUtf16(g) => g.next(),
+            NativeSegmentIterator::WordUtf16(w) => w.next(),
+            NativeSegmentIterator::SentenceUtf16(s) => s.next(),
+            NativeSegmentIterator::GraphemeLatin1(g) => g.next(),
+            NativeSegmentIterator::WordLatin1(w) => w.next(),
+            NativeSegmentIterator::SentenceLatin1(s) => s.next(),
         }
     }
 }
@@ -37,10 +45,10 @@ impl NativeSegmentIterator<'_, '_> {
     /// If the iterator is a word break iterator, returns `Some(true)` when the segment preceding
     /// the current boundary is word-like.
     pub(crate) fn is_word_like(&self) -> Option<bool> {
-        if let Self::Word(w) = self {
-            Some(w.is_word_like())
-        } else {
-            None
+        match self {
+            Self::WordLatin1(w) => Some(w.is_word_like()),
+            Self::WordUtf16(w) => Some(w.is_word_like()),
+            _ => None,
         }
     }
 }

core/engine/src/builtins/intl/segmenter/mod.rs

@@ -1,7 +1,7 @@
 use std::ops::Range;
 
 use boa_gc::{Finalize, Trace};
-use boa_macros::utf16;
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use icu_locid::Locale;
 use icu_segmenter::{
@@ -19,7 +19,7 @@ use crate::{
     property::Attribute,
     realm::Realm,
     string::common::StaticJsStrings,
-    Context, JsArgs, JsData, JsNativeError, JsResult, JsString, JsSymbol, JsValue,
+    Context, JsArgs, JsData, JsNativeError, JsResult, JsStr, JsString, JsSymbol, JsValue,
 };
 
 mod iterator;
@@ -62,11 +62,18 @@ impl NativeSegmenter {
 
     /// Segment the passed string, returning an iterator with the index boundaries
     /// of the segments.
-    pub(crate) fn segment<'l, 's>(&'l self, input: &'s [u16]) -> NativeSegmentIterator<'l, 's> {
-        match self {
-            Self::Grapheme(g) => NativeSegmentIterator::Grapheme(g.segment_utf16(input)),
-            Self::Word(w) => NativeSegmentIterator::Word(w.segment_utf16(input)),
-            Self::Sentence(s) => NativeSegmentIterator::Sentence(s.segment_utf16(input)),
+    pub(crate) fn segment<'l, 's>(&'l self, input: JsStr<'s>) -> NativeSegmentIterator<'l, 's> {
+        match input.variant() {
+            crate::string::JsStrVariant::Latin1(input) => match self {
+                Self::Grapheme(g) => NativeSegmentIterator::GraphemeLatin1(g.segment_latin1(input)),
+                Self::Word(w) => NativeSegmentIterator::WordLatin1(w.segment_latin1(input)),
+                Self::Sentence(s) => NativeSegmentIterator::SentenceLatin1(s.segment_latin1(input)),
+            },
+            crate::string::JsStrVariant::Utf16(input) => match self {
+                Self::Grapheme(g) => NativeSegmentIterator::GraphemeUtf16(g.segment_utf16(input)),
+                Self::Word(w) => NativeSegmentIterator::WordUtf16(w.segment_utf16(input)),
+                Self::Sentence(s) => NativeSegmentIterator::SentenceUtf16(s.segment_utf16(input)),
+            },
         }
     }
 }
@@ -134,7 +141,7 @@ impl BuiltInConstructor for Segmenter {
 
         // 6. Let opt be a new Record.
         // 7. Let matcher be ? GetOption(options, "localeMatcher", string, « "lookup", "best fit" », "best fit").
-        let matcher = get_option(&options, utf16!("localeMatcher"), context)?.unwrap_or_default();
+        let matcher = get_option(&options, js_str!("localeMatcher"), context)?.unwrap_or_default();
 
         // 8. Set opt.[[localeMatcher]] to matcher.
         // 9. Let localeData be %Segmenter%.[[LocaleData]].
@@ -150,7 +157,8 @@ impl BuiltInConstructor for Segmenter {
         );
 
         // 12. Let granularity be ? GetOption(options, "granularity", string, « "grapheme", "word", "sentence" », "grapheme").
-        let granularity = get_option(&options, utf16!("granularity"), context)?.unwrap_or_default();
+        let granularity =
+            get_option(&options, js_str!("granularity"), context)?.unwrap_or_default();
         // 13. Set segmenter.[[SegmenterGranularity]] to granularity.
 
         let native = match granularity {
@@ -241,12 +249,12 @@ impl Segmenter {
         //     d. Perform ! CreateDataPropertyOrThrow(options, p, v).
         let options = ObjectInitializer::new(context)
             .property(
-                js_string!("locale"),
+                js_str!("locale"),
                 js_string!(segmenter.locale.to_string()),
                 Attribute::all(),
             )
             .property(
-                js_string!("granularity"),
+                js_str!("granularity"),
                 js_string!(segmenter.native.granularity().to_string()),
                 Attribute::all(),
             )
@@ -301,25 +309,25 @@ fn create_segment_data_object(
     let start = range.start;
 
     // 6. Let segment be the substring of string from startIndex to endIndex.
-    let segment = js_string!(&string[range]);
+    let segment = string.get(range).expect("range already checked");
 
     // 5. Let result be OrdinaryObjectCreate(%Object.prototype%).
     let object = &mut ObjectInitializer::new(context);
 
     object
         // 7. Perform ! CreateDataPropertyOrThrow(result, "segment", segment).
-        .property(js_string!("segment"), segment, Attribute::all())
+        .property(js_str!("segment"), segment, Attribute::all())
         // 8. Perform ! CreateDataPropertyOrThrow(result, "index", 𝔽(startIndex)).
-        .property(js_string!("index"), start, Attribute::all())
+        .property(js_str!("index"), start, Attribute::all())
         // 9. Perform ! CreateDataPropertyOrThrow(result, "input", string).
-        .property(js_string!("input"), string, Attribute::all());
+        .property(js_str!("input"), string, Attribute::all());
 
     // 10. Let granularity be segmenter.[[SegmenterGranularity]].
     // 11. If granularity is "word", then
     if let Some(is_word_like) = is_word_like {
         //     a. Let isWordLike be a Boolean value indicating whether the segment in string is "word-like" according to locale segmenter.[[Locale]].
         //     b. Perform ! CreateDataPropertyOrThrow(result, "isWordLike", isWordLike).
-        object.property(js_string!("isWordLike"), is_word_like, Attribute::all());
+        object.property(js_str!("isWordLike"), is_word_like, Attribute::all());
     }
 
     // 12. Return result.

core/engine/src/builtins/intl/segmenter/segments.rs

@@ -89,7 +89,7 @@ impl Segments {
         // 8. Let startIndex be ! FindBoundary(segmenter, string, n, before).
         // 9. Let endIndex be ! FindBoundary(segmenter, string, n, after).
         let (range, is_word_like) = {
-            let mut segments = segmenter.native.segment(&segments.string);
+            let mut segments = segmenter.native.segment(segments.string.as_str());
             std::iter::from_fn(|| segments.next().map(|i| (i, segments.is_word_like())))
                 .tuple_windows()
                 .find(|((i, _), (j, _))| (*i..*j).contains(&n))

core/engine/src/builtins/iterable/async_from_sync_iterator.rs

@@ -9,10 +9,10 @@ use crate::{
     native_function::NativeFunction,
     object::{FunctionObjectBuilder, JsObject},
     realm::Realm,
-    string::utf16,
     Context, JsArgs, JsData, JsError, JsNativeError, JsResult, JsValue,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 /// `%AsyncFromSyncIteratorPrototype%` object.
@@ -80,7 +80,7 @@ impl AsyncFromSyncIterator {
 
         // 3. Let nextMethod be ! Get(asyncIterator, "next").
         let next_method = async_iterator
-            .get(utf16!("next"), context)
+            .get(js_str!("next"), context)
             .expect("async from sync iterator prototype must have next method");
 
         // 4. Let iteratorRecord be the Iterator Record { [[Iterator]]: asyncIterator, [[NextMethod]]: nextMethod, [[Done]]: false }.
@@ -166,7 +166,7 @@ impl AsyncFromSyncIterator {
         .expect("cannot fail with promise constructor");
 
         // 6. Let return be Completion(GetMethod(syncIterator, "return")).
-        let r#return = sync_iterator.get_method(utf16!("return"), context);
+        let r#return = sync_iterator.get_method(js_str!("return"), context);
 
         // 7. IfAbruptRejectPromise(return, promiseCapability).
         let r#return = if_abrupt_reject_promise!(r#return, promise_capability, context);
@@ -243,7 +243,7 @@ impl AsyncFromSyncIterator {
         .expect("cannot fail with promise constructor");
 
         // 6. Let throw be Completion(GetMethod(syncIterator, "throw")).
-        let throw = sync_iterator.get_method(utf16!("throw"), context);
+        let throw = sync_iterator.get_method(js_str!("throw"), context);
 
         // 7. IfAbruptRejectPromise(throw, promiseCapability).
         let throw = if_abrupt_reject_promise!(throw, promise_capability, context);
@@ -368,7 +368,7 @@ impl AsyncFromSyncIterator {
                 ))
             }),
         )
-        .name("")
+        .name(js_str!(""))
         .length(1)
         .build();
 
@@ -401,7 +401,7 @@ impl AsyncFromSyncIterator {
                         sync_iterator_record,
                     ),
                 )
-                .name("")
+                .name(js_str!(""))
                 .length(1)
                 .build(),
             )

core/engine/src/builtins/iterable/mod.rs

@@ -4,13 +4,13 @@ use crate::{
     builtins::{BuiltInBuilder, IntrinsicObject},
     context::intrinsics::Intrinsics,
     error::JsNativeError,
-    js_string,
     object::JsObject,
     realm::Realm,
     symbol::JsSymbol,
     Context, JsResult, JsValue,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 mod async_from_sync_iterator;
@@ -282,7 +282,7 @@ impl JsValue {
         })?;
 
         // 5. Let nextMethod be ? GetV(iterator, "next").
-        let next_method = iterator.get_v(js_string!("next"), context)?;
+        let next_method = iterator.get_v(js_str!("next"), context)?;
 
         // 6. Let iteratorRecord be the Record { [[Iterator]]: iterator, [[NextMethod]]: nextMethod, [[Done]]: false }.
         // 7. Return iteratorRecord.
@@ -326,7 +326,7 @@ impl IteratorResult {
     #[inline]
     pub fn complete(&self, context: &mut Context) -> JsResult<bool> {
         // 1. Return ToBoolean(? Get(iterResult, "done")).
-        Ok(self.object.get(js_string!("done"), context)?.to_boolean())
+        Ok(self.object.get(js_str!("done"), context)?.to_boolean())
     }
 
     /// `IteratorValue ( iterResult )`
@@ -342,7 +342,7 @@ impl IteratorResult {
     #[inline]
     pub fn value(&self, context: &mut Context) -> JsResult<JsValue> {
         // 1. Return ? Get(iterResult, "value").
-        self.object.get(js_string!("value"), context)
+        self.object.get(js_str!("value"), context)
     }
 }
 
@@ -524,7 +524,7 @@ impl IteratorRecord {
         let iterator = &self.iterator;
 
         // 3. Let innerResult be Completion(GetMethod(iterator, "return")).
-        let inner_result = iterator.get_method(js_string!("return"), context);
+        let inner_result = iterator.get_method(js_str!("return"), context);
 
         // 4. If innerResult.[[Type]] is normal, then
         let inner_result = match inner_result {

core/engine/src/builtins/json/mod.rs

@@ -15,6 +15,7 @@
 
 use std::{borrow::Cow, iter::once};
 
+use boa_macros::{js_str, utf16};
 use itertools::Itertools;
 
 use crate::{
@@ -26,7 +27,7 @@ use crate::{
     object::{internal_methods::InternalMethodContext, JsObject},
     property::{Attribute, PropertyNameKind},
     realm::Realm,
-    string::{common::StaticJsStrings, utf16, CodePoint},
+    string::{common::StaticJsStrings, CodePoint},
     symbol::JsSymbol,
     value::IntegerOrInfinity,
     vm::{CallFrame, CallFrameFlags},
@@ -148,11 +149,11 @@ impl Json {
 
             // b. Let rootName be the empty String.
             // c. Perform ! CreateDataPropertyOrThrow(root, rootName, unfiltered).
-            root.create_data_property_or_throw(utf16!(""), unfiltered, context)
+            root.create_data_property_or_throw(js_str!(""), unfiltered, context)
                 .expect("CreateDataPropertyOrThrow should never throw here");
 
             // d. Return ? InternalizeJSONProperty(root, rootName, reviver).
-            Self::internalize_json_property(&root, "".into(), obj, context)
+            Self::internalize_json_property(&root, js_string!(), obj, context)
         } else {
             // 12. Else,
             // a. Return unfiltered.
@@ -368,7 +369,7 @@ impl Json {
         // 7. Else if Type(space) is String, then
         } else if let Some(s) = space.as_string() {
             // a. If the length of space is 10 or less, let gap be space; otherwise let gap be the substring of space from 0 to 10.
-            js_string!(s.get(..10).unwrap_or(s))
+            js_string!(s.get(..10).unwrap_or(s.as_str()))
         // 8. Else,
         } else {
             // a. Let gap be the empty String.
@@ -380,7 +381,7 @@ impl Json {
 
         // 10. Perform ! CreateDataPropertyOrThrow(wrapper, the empty String, value).
         wrapper
-            .create_data_property_or_throw(utf16!(""), args.get_or_undefined(0).clone(), context)
+            .create_data_property_or_throw(js_str!(""), args.get_or_undefined(0).clone(), context)
             .expect("CreateDataPropertyOrThrow should never fail here");
 
         // 11. Let state be the Record { [[ReplacerFunction]]: ReplacerFunction, [[Stack]]: stack, [[Indent]]: indent, [[Gap]]: gap, [[PropertyList]]: PropertyList }.
@@ -418,7 +419,7 @@ impl Json {
         // 2. If Type(value) is Object or BigInt, then
         if value.is_object() || value.is_bigint() {
             // a. Let toJSON be ? GetV(value, "toJSON").
-            let to_json = value.get_v(utf16!("toJSON"), context)?;
+            let to_json = value.get_v(js_str!("toJSON"), context)?;
 
             // b. If IsCallable(toJSON) is true, then
             if let Some(obj) = to_json.as_object() {
@@ -627,7 +628,7 @@ impl Json {
             // b. If strP is not undefined, then
             if let Some(str_p) = str_p {
                 // i. Let member be QuoteJSONString(P).
-                let mut member = Self::quote_json_string(p).to_vec();
+                let mut member = Self::quote_json_string(p).iter().collect::<Vec<_>>();
 
                 // ii. Set member to the string-concatenation of member and ":".
                 member.push(':' as u16);
@@ -639,7 +640,7 @@ impl Json {
                 }
 
                 // iv. Set member to the string-concatenation of member and strP.
-                member.extend_from_slice(&str_p);
+                member.extend(str_p.iter());
 
                 // v. Append member to partial.
                 partial.push(member);
@@ -674,20 +675,20 @@ impl Json {
                 // i. Let separator be the string-concatenation of the code unit 0x002C (COMMA),
                 //    the code unit 0x000A (LINE FEED), and state.[[Indent]].
                 let mut separator = utf16!(",\n").to_vec();
-                separator.extend_from_slice(&state.indent);
+                separator.extend(state.indent.iter());
                 // ii. Let properties be the String value formed by concatenating all the element Strings of partial
                 //     with each adjacent pair of Strings separated with separator.
                 //     The separator String is not inserted either before the first String or after the last String.
                 // iii. Let final be the string-concatenation of "{", the code
                 //      unit 0x000A (LINE FEED), state.[[Indent]], properties,
                 //      the code unit 0x000A (LINE FEED), stepback, and "}".
-                let result = [utf16!("{\n"), &state.indent[..]]
+                let result = [utf16!("{\n"), &state.indent.to_vec()[..]]
                     .into_iter()
                     .chain(Itertools::intersperse(
                         partial.iter().map(Vec::as_slice),
                         &separator,
                     ))
-                    .chain([utf16!("\n"), &stepback[..], utf16!("}")])
+                    .chain([utf16!("\n"), &stepback.to_vec()[..], utf16!("}")])
                     .flatten()
                     .copied()
                     .collect::<Vec<_>>();
@@ -750,7 +751,7 @@ impl Json {
             // b. If strP is undefined, then
             if let Some(str_p) = str_p {
                 // i. Append strP to partial.
-                partial.push(Cow::Owned(str_p.to_vec()));
+                partial.push(Cow::Owned(str_p.iter().collect::<_>()));
             // c. Else,
             } else {
                 // i. Append "null" to partial.
@@ -789,18 +790,18 @@ impl Json {
                 // i. Let separator be the string-concatenation of the code unit 0x002C (COMMA),
                 //    the code unit 0x000A (LINE FEED), and state.[[Indent]].
                 let mut separator = utf16!(",\n").to_vec();
-                separator.extend_from_slice(&state.indent);
+                separator.extend(state.indent.iter());
                 // ii. Let properties be the String value formed by concatenating all the element Strings of partial
                 //     with each adjacent pair of Strings separated with separator.
                 //     The separator String is not inserted either before the first String or after the last String.
                 // iii. Let final be the string-concatenation of "[", the code unit 0x000A (LINE FEED), state.[[Indent]], properties, the code unit 0x000A (LINE FEED), stepback, and "]".
-                let result = [utf16!("[\n"), &state.indent[..]]
+                let result = [utf16!("[\n"), &state.indent.to_vec()[..]]
                     .into_iter()
                     .chain(Itertools::intersperse(
                         partial.iter().map(Cow::as_ref),
                         &separator,
                     ))
-                    .chain([utf16!("\n"), &stepback[..], utf16!("]")])
+                    .chain([utf16!("\n"), &stepback.to_vec()[..], utf16!("]")])
                     .flatten()
                     .copied()
                     .collect::<Vec<_>>();

core/engine/src/builtins/json/tests.rs

@@ -1,3 +1,4 @@
+use boa_macros::js_str;
 use indoc::indoc;
 
 use crate::{js_string, run_test_actions, JsNativeErrorKind, JsValue, TestAction};
@@ -5,7 +6,7 @@ use crate::{js_string, run_test_actions, JsNativeErrorKind, JsValue, TestAction}
 #[test]
 fn json_sanity() {
     run_test_actions([
-        TestAction::assert_eq(r#"JSON.parse('{"aaa":"bbb"}').aaa"#, js_string!("bbb")),
+        TestAction::assert_eq(r#"JSON.parse('{"aaa":"bbb"}').aaa"#, js_str!("bbb")),
         TestAction::assert_eq(
             r#"JSON.stringify({aaa: 'bbb'})"#,
             js_string!(r#"{"aaa":"bbb"}"#),
@@ -89,7 +90,7 @@ fn json_stringify_object_array() {
 fn json_stringify_array_converts_undefined_to_null() {
     run_test_actions([TestAction::assert_eq(
         "JSON.stringify([undefined])",
-        js_string!("[null]"),
+        js_str!("[null]"),
     )]);
 }
 
@@ -97,7 +98,7 @@ fn json_stringify_array_converts_undefined_to_null() {
 fn json_stringify_array_converts_function_to_null() {
     run_test_actions([TestAction::assert_eq(
         "JSON.stringify([() => {}])",
-        js_string!("[null]"),
+        js_str!("[null]"),
     )]);
 }
 
@@ -105,7 +106,7 @@ fn json_stringify_array_converts_function_to_null() {
 fn json_stringify_array_converts_symbol_to_null() {
     run_test_actions([TestAction::assert_eq(
         "JSON.stringify([Symbol()])",
-        js_string!("[null]"),
+        js_str!("[null]"),
     )]);
 }
 #[test]
@@ -150,10 +151,7 @@ fn json_stringify_no_args() {
 
 #[test]
 fn json_stringify_fractional_numbers() {
-    run_test_actions([TestAction::assert_eq(
-        "JSON.stringify(1.2)",
-        js_string!("1.2"),
-    )]);
+    run_test_actions([TestAction::assert_eq("JSON.stringify(1.2)", js_str!("1.2"))]);
 }
 
 #[test]
@@ -278,8 +276,8 @@ fn json_parse_object_with_reviver() {
 
                 var jsonObj = JSON.parse(jsonString, dataReviver);
             "#}),
-        TestAction::assert_eq("jsonObj.firstname", js_string!("boa")),
-        TestAction::assert_eq("jsonObj.lastname", js_string!("interpreter")),
+        TestAction::assert_eq("jsonObj.firstname", js_str!("boa")),
+        TestAction::assert_eq("jsonObj.lastname", js_str!("interpreter")),
     ]);
 }
 

core/engine/src/builtins/map/mod.rs

@@ -18,10 +18,11 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::{Attribute, PropertyNameKind},
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     symbol::JsSymbol,
     Context, JsArgs, JsResult, JsString, JsValue,
 };
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use num_traits::Zero;
 
@@ -63,7 +64,7 @@ impl IntrinsicObject for Map {
                 Attribute::CONFIGURABLE,
             )
             .property(
-                utf16!("entries"),
+                js_string!("entries"),
                 entries_function.clone(),
                 Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
             )
@@ -148,7 +149,7 @@ impl BuiltInConstructor for Map {
         };
 
         // 5. Let adder be ? Get(map, "set").
-        let adder = map.get(utf16!("set"), context)?;
+        let adder = map.get(js_str!("set"), context)?;
 
         // 6. Return ? AddEntriesFromIterable(map, iterable, adder).
         add_entries_from_iterable(&map, iterable, &adder, context)

core/engine/src/builtins/map/tests.rs

@@ -1,4 +1,5 @@
-use crate::{js_string, run_test_actions, JsNativeErrorKind, JsValue, TestAction};
+use crate::{run_test_actions, JsNativeErrorKind, JsValue, TestAction};
+use boa_macros::js_str;
 use indoc::indoc;
 
 #[test]
@@ -74,7 +75,7 @@ fn merge() {
                 let merged2 = new Map([...second, ...third]);
             "#}),
         TestAction::assert_eq("merged1.size", 3),
-        TestAction::assert_eq("merged1.get('2')", js_string!("second two")),
+        TestAction::assert_eq("merged1.get('2')", js_str!("second two")),
         TestAction::assert_eq("merged2.size", 4),
     ]);
 }
@@ -85,8 +86,8 @@ fn get() {
         TestAction::run(indoc! {r#"
                 let map = new Map([["1", "one"], ["2", "two"]]);
             "#}),
-        TestAction::assert_eq("map.get('1')", js_string!("one")),
-        TestAction::assert_eq("map.get('2')", js_string!("two")),
+        TestAction::assert_eq("map.get('1')", js_str!("one")),
+        TestAction::assert_eq("map.get('2')", js_str!("two")),
         TestAction::assert_eq("map.get('3')", JsValue::undefined()),
         TestAction::assert_eq("map.get()", JsValue::undefined()),
     ]);
@@ -98,7 +99,7 @@ fn set() {
         TestAction::run("let map = new Map();"),
         TestAction::assert("map.set(); map.has(undefined)"),
         TestAction::assert_eq("map.get()", JsValue::undefined()),
-        TestAction::assert_eq("map.set('1', 'one'); map.get('1')", js_string!("one")),
+        TestAction::assert_eq("map.set('1', 'one'); map.get('1')", js_str!("one")),
         TestAction::assert("map.set('2'); map.has('2')"),
         TestAction::assert_eq("map.get('2')", JsValue::undefined()),
     ]);
@@ -148,7 +149,7 @@ fn keys() {
                 let item2 = keysIterator.next();
                 let item3 = keysIterator.next();
             "#}),
-        TestAction::assert_eq("item1.value", js_string!("0")),
+        TestAction::assert_eq("item1.value", js_str!("0")),
         TestAction::assert_eq("item2.value", 1),
         TestAction::assert("item3.done"),
     ]);
@@ -187,8 +188,8 @@ fn values() {
                 let item2 = valuesIterator.next();
                 let item3 = valuesIterator.next();
             "#}),
-        TestAction::assert_eq("item1.value", js_string!("foo")),
-        TestAction::assert_eq("item2.value", js_string!("bar")),
+        TestAction::assert_eq("item1.value", js_str!("foo")),
+        TestAction::assert_eq("item2.value", js_str!("bar")),
         TestAction::assert("item3.done"),
     ]);
 }
@@ -201,7 +202,7 @@ fn modify_key() {
                 let map = new Map([[obj, "one"]]);
                 obj.field = "Value";
             "#}),
-        TestAction::assert_eq("map.get(obj)", js_string!("one")),
+        TestAction::assert_eq("map.get(obj)", js_str!("one")),
     ]);
 }
 

core/engine/src/builtins/mod.rs

@@ -36,6 +36,7 @@ pub mod weak_set;
 
 mod builder;
 
+use boa_macros::js_str;
 use builder::BuiltInBuilder;
 
 #[cfg(feature = "annex-b")]
@@ -108,7 +109,6 @@ use crate::{
     object::JsObject,
     property::{Attribute, PropertyDescriptor},
     realm::Realm,
-    string::utf16,
     Context, JsResult, JsString, JsValue,
 };
 
@@ -307,7 +307,7 @@ pub(crate) fn set_default_global_bindings(context: &mut Context) -> JsResult<()>
     let global_object = context.global_object();
 
     global_object.define_property_or_throw(
-        utf16!("globalThis"),
+        js_str!("globalThis"),
         PropertyDescriptor::builder()
             .value(context.realm().global_this().clone())
             .writable(true)
@@ -320,17 +320,17 @@ pub(crate) fn set_default_global_bindings(context: &mut Context) -> JsResult<()>
         .enumerable(false)
         .configurable(false);
     global_object.define_property_or_throw(
-        utf16!("Infinity"),
+        js_str!("Infinity"),
         restricted.clone().value(f64::INFINITY),
         context,
     )?;
     global_object.define_property_or_throw(
-        utf16!("NaN"),
+        js_str!("NaN"),
         restricted.clone().value(f64::NAN),
         context,
     )?;
     global_object.define_property_or_throw(
-        utf16!("undefined"),
+        js_str!("undefined"),
         restricted.value(JsValue::undefined()),
         context,
     )?;

core/engine/src/builtins/number/globals.rs

@@ -1,15 +1,13 @@
-use boa_macros::utf16;
-
 use crate::{
     builtins::{string::is_trimmable_whitespace, BuiltInBuilder, BuiltInObject, IntrinsicObject},
     context::intrinsics::Intrinsics,
     object::JsObject,
     realm::Realm,
-    string::{common::StaticJsStrings, Utf16Trim},
-    Context, JsArgs, JsResult, JsString, JsValue,
+    string::common::StaticJsStrings,
+    Context, JsArgs, JsResult, JsStr, JsString, JsValue,
 };
 
-use num_traits::Num;
+use boa_macros::js_str;
 
 /// Builtin javascript 'isFinite(number)' function.
 ///
@@ -95,6 +93,55 @@ impl BuiltInObject for IsNaN {
     const NAME: JsString = StaticJsStrings::IS_NAN;
 }
 
+fn from_js_str_radix(src: JsStr<'_>, radix: u8) -> Option<f64> {
+    /// Determines if a string of text of that length of that radix could be guaranteed to be
+    /// stored in the given type T.
+    /// Note that if the radix is known to the compiler, it is just the check of digits.len that
+    /// is done at runtime.
+    fn can_not_overflow(radix: u8, digits_len: usize) -> bool {
+        usize::from(radix) <= 16 && digits_len <= std::mem::size_of::<u64>() * 2
+    }
+
+    const fn to_digit(input: u8, radix: u8) -> Option<u8> {
+        // If not a digit, a number greater than radix will be created.
+        let mut digit = input.wrapping_sub(b'0');
+        if radix > 10 {
+            debug_assert!(radix <= 36, "to_digit: radix is too high (maximum 36)");
+            if digit < 10 {
+                return Some(digit);
+            }
+            // Force the 6th bit to be set to ensure ascii is lower case.
+            digit = (input | 0b10_0000).wrapping_sub(b'a').saturating_add(10);
+        }
+        // FIXME: once then_some is const fn, use it here
+        if digit < radix {
+            Some(digit)
+        } else {
+            None
+        }
+    }
+
+    let src = src
+        .iter()
+        .map(|x| u8::try_from(x).expect("should be ascii string"));
+
+    let result = if can_not_overflow(radix, src.len()) {
+        let mut result = 0;
+        for c in src {
+            result = result * u64::from(radix) + u64::from(to_digit(c, radix)?);
+        }
+        result as f64
+    } else {
+        let mut result = 0f64;
+        for c in src {
+            result = result * f64::from(radix) + f64::from(to_digit(c, radix)?);
+        }
+        result
+    };
+
+    Some(result)
+}
+
 /// Builtin javascript 'parseInt(str, radix)' function.
 ///
 /// Parses the given string as an integer using the given radix as a base.
@@ -110,107 +157,108 @@ impl BuiltInObject for IsNaN {
 /// [spec]: https://tc39.es/ecma262/#sec-parseint-string-radix
 /// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt
 pub(crate) fn parse_int(_: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
-    if let (Some(val), radix) = (args.first(), args.get_or_undefined(1)) {
-        // 1. Let inputString be ? ToString(string).
-        let input_string = val.to_string(context)?;
-
-        // 2. Let S be ! TrimString(inputString, start).
-        let mut var_s = input_string.trim_start();
-
-        // 3. Let sign be 1.
-        // 4. If S is not empty and the first code unit of S is the code unit 0x002D (HYPHEN-MINUS),
-        //    set sign to -1.
-        let sign = if !var_s.is_empty() && var_s.starts_with(utf16!("-")) {
-            -1
-        } else {
-            1
-        };
+    let (Some(val), radix) = (args.first(), args.get_or_undefined(1)) else {
+        // Not enough arguments to parseInt.
+        return Ok(JsValue::nan());
+    };
 
-        // 5. If S is not empty and the first code unit of S is the code unit 0x002B (PLUS SIGN) or
-        //    the code unit 0x002D (HYPHEN-MINUS), remove the first code unit from S.
-        if !var_s.is_empty() && (var_s.starts_with(utf16!("+")) || var_s.starts_with(utf16!("-"))) {
-            var_s = &var_s[1..];
-        }
+    // 1. Let inputString be ? ToString(string).
+    let input_string = val.to_string(context)?;
 
-        // 6. Let R be ℝ(? ToInt32(radix)).
-        let mut var_r = radix.to_i32(context)?;
+    // 2. Let S be ! TrimString(inputString, start).
+    let mut s = input_string.trim_start();
+    // let mut
 
-        // 7. Let stripPrefix be true.
-        let mut strip_prefix = true;
+    // 3. Let sign be 1.
+    // 4. If S is not empty and the first code unit of S is the code unit 0x002D (HYPHEN-MINUS),
+    //    set sign to -1.
+    let sign = if !s.is_empty() && s.starts_with(js_str!("-")) {
+        -1
+    } else {
+        1
+    };
 
-        // 8. If R ≠ 0, then
-        #[allow(clippy::if_not_else)]
-        if var_r != 0 {
-            //     a. If R < 2 or R > 36, return NaN.
-            if !(2..=36).contains(&var_r) {
-                return Ok(JsValue::nan());
-            }
+    // 5. If S is not empty and the first code unit of S is the code unit 0x002B (PLUS SIGN) or
+    //    the code unit 0x002D (HYPHEN-MINUS), remove the first code unit from S.
+    if !s.is_empty() && (s.starts_with(js_str!("+")) || s.starts_with(js_str!("-"))) {
+        s = s.get(1..).expect("already checked that it's not empty");
+    }
 
-            //     b. If R ≠ 16, set stripPrefix to false.
-            if var_r != 16 {
-                strip_prefix = false;
-            }
-        } else {
-            // 9. Else,
-            //     a. Set R to 10.
-            var_r = 10;
-        }
+    // 6. Let R be ℝ(? ToInt32(radix)).
+    let r = radix.to_i32(context)?;
 
-        // 10. If stripPrefix is true, then
-        //     a. If the length of S is at least 2 and the first two code units of S are either "0x" or "0X", then
-        //         i. Remove the first two code units from S.
-        //         ii. Set R to 16.
-        if strip_prefix
-            && var_s.len() >= 2
-            && (var_s.starts_with(utf16!("0x")) || var_s.starts_with(utf16!("0X")))
-        {
-            var_s = &var_s[2..];
+    // 7. Let stripPrefix be true.
+    let mut strip_prefix = true;
 
-            var_r = 16;
+    // 8. If R ≠ 0, then
+    #[allow(clippy::if_not_else)]
+    let mut r = if r != 0 {
+        //     a. If R < 2 or R > 36, return NaN.
+        if !(2..=36).contains(&r) {
+            return Ok(JsValue::nan());
         }
 
-        // 11. If S contains a code unit that is not a radix-R digit, let end be the index within S of the
-        //     first such code unit; otherwise, let end be the length of S.
-        let end = char::decode_utf16(var_s.iter().copied())
-            .position(|code| !code.is_ok_and(|c| c.is_digit(var_r as u32)))
-            .unwrap_or(var_s.len());
+        //     b. If R ≠ 16, set stripPrefix to false.
+        if r != 16 {
+            strip_prefix = false;
+        }
+        r as u8
+    } else {
+        // 9. Else,
+        //     a. Set R to 10.
+        10
+    };
+
+    // 10. If stripPrefix is true, then
+    //     a. If the length of S is at least 2 and the first two code units of S are either "0x" or "0X", then
+    //         i. Remove the first two code units from S.
+    //         ii. Set R to 16.
+    if strip_prefix
+        && s.len() >= 2
+        && (s.starts_with(js_str!("0x")) || s.starts_with(js_str!("0X")))
+    {
+        s = s
+            .get(2..)
+            .expect("already checked that it contains at least two chars");
+
+        r = 16;
+    }
 
-        // 12. Let Z be the substring of S from 0 to end.
-        let var_z = String::from_utf16_lossy(&var_s[..end]);
+    // 11. If S contains a code unit that is not a radix-R digit, let end be the index within S of the
+    //     first such code unit; otherwise, let end be the length of S.
+    let end = char::decode_utf16(s.iter())
+        .position(|code| !code.is_ok_and(|c| c.is_digit(u32::from(r))))
+        .unwrap_or(s.len());
 
-        // 13. If Z is empty, return NaN.
-        if var_z.is_empty() {
-            return Ok(JsValue::nan());
-        }
+    // 12. Let Z be the substring of S from 0 to end.
+    let z = s.get(..end).expect("should be in range");
 
-        // 14. Let mathInt be the integer value that is represented by Z in radix-R notation, using the
-        //     letters A-Z and a-z for digits with values 10 through 35. (However, if R is 10 and Z contains
-        //     more than 20 significant digits, every significant digit after the 20th may be replaced by a
-        //     0 digit, at the option of the implementation; and if R is not 2, 4, 8, 10, 16, or 32, then
-        //     mathInt may be an implementation-approximated value representing the integer value that is
-        //     represented by Z in radix-R notation.)
-        let math_int = u64::from_str_radix(&var_z, var_r as u32).map_or_else(
-            |_| f64::from_str_radix(&var_z, var_r as u32).expect("invalid_float_conversion"),
-            |i| i as f64,
-        );
-
-        // 15. If mathInt = 0, then
-        //     a. If sign = -1, return -0𝔽.
-        //     b. Return +0𝔽.
-        if math_int == 0_f64 {
-            if sign == -1 {
-                return Ok(JsValue::new(-0_f64));
-            }
+    // 13. If Z is empty, return NaN.
+    if z.is_empty() {
+        return Ok(JsValue::nan());
+    }
 
-            return Ok(JsValue::new(0_f64));
+    // 14. Let mathInt be the integer value that is represented by Z in radix-R notation, using the
+    //     letters A-Z and a-z for digits with values 10 through 35. (However, if R is 10 and Z contains
+    //     more than 20 significant digits, every significant digit after the 20th may be replaced by a
+    //     0 digit, at the option of the implementation; and if R is not 2, 4, 8, 10, 16, or 32, then
+    //     mathInt may be an implementation-approximated value representing the integer value that is
+    //     represented by Z in radix-R notation.)
+    let math_int = from_js_str_radix(z, r).expect("Already checked");
+
+    // 15. If mathInt = 0, then
+    //     a. If sign = -1, return -0𝔽.
+    //     b. Return +0𝔽.
+    if math_int == 0_f64 {
+        if sign == -1 {
+            return Ok(JsValue::new(-0_f64));
         }
 
-        // 16. Return 𝔽(sign × mathInt).
-        Ok(JsValue::new(f64::from(sign) * math_int))
-    } else {
-        // Not enough arguments to parseInt.
-        Ok(JsValue::nan())
+        return Ok(JsValue::new(0_f64));
     }
+
+    // 16. Return 𝔽(sign × mathInt).
+    Ok(JsValue::new(f64::from(sign) * math_int))
 }
 
 pub(crate) struct ParseInt;

core/engine/src/builtins/number/mod.rs

@@ -25,6 +25,7 @@ use crate::{
     value::{AbstractRelation, IntegerOrInfinity, JsValue},
     Context, JsArgs, JsResult, JsString,
 };
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use num_traits::float::FloatCore;
 
@@ -690,13 +691,13 @@ impl Number {
         }
 
         if x == -0. {
-            return Ok(JsValue::new(js_string!("0")));
+            return Ok(JsValue::new(js_str!("0")));
         } else if x.is_nan() {
-            return Ok(JsValue::new(js_string!("NaN")));
+            return Ok(JsValue::new(js_str!("NaN")));
         } else if x.is_infinite() && x.is_sign_positive() {
-            return Ok(JsValue::new(js_string!("Infinity")));
+            return Ok(JsValue::new(js_str!("Infinity")));
         } else if x.is_infinite() && x.is_sign_negative() {
-            return Ok(JsValue::new(js_string!("-Infinity")));
+            return Ok(JsValue::new(js_str!("-Infinity")));
         }
 
         // This is a Optimization from the v8 source code to print values that can fit in a single character

core/engine/src/builtins/number/tests.rs

@@ -1,11 +1,12 @@
+use boa_macros::js_str;
+
 use crate::{
-    builtins::Number, js_string, run_test_actions, value::AbstractRelation, JsNativeErrorKind,
-    TestAction,
+    builtins::Number, run_test_actions, value::AbstractRelation, JsNativeErrorKind, TestAction,
 };
 
 #[test]
 fn integer_number_primitive_to_number_object() {
-    run_test_actions([TestAction::assert_eq("(100).toString()", js_string!("100"))]);
+    run_test_actions([TestAction::assert_eq("(100).toString()", js_str!("100"))]);
 }
 
 #[test]
@@ -25,136 +26,133 @@ fn call_number() {
 #[test]
 fn to_exponential() {
     run_test_actions([
-        TestAction::assert_eq("Number().toExponential()", js_string!("0e+0")),
-        TestAction::assert_eq("Number(5).toExponential()", js_string!("5e+0")),
-        TestAction::assert_eq("Number(1.234).toExponential()", js_string!("1.234e+0")),
-        TestAction::assert_eq("Number(1234).toExponential()", js_string!("1.234e+3")),
+        TestAction::assert_eq("Number().toExponential()", js_str!("0e+0")),
+        TestAction::assert_eq("Number(5).toExponential()", js_str!("5e+0")),
+        TestAction::assert_eq("Number(1.234).toExponential()", js_str!("1.234e+0")),
+        TestAction::assert_eq("Number(1234).toExponential()", js_str!("1.234e+3")),
         TestAction::assert_eq(
             "Number('I am also not a number').toExponential()",
-            js_string!("NaN"),
+            js_str!("NaN"),
         ),
-        TestAction::assert_eq("Number('1.23e+2').toExponential()", js_string!("1.23e+2")),
+        TestAction::assert_eq("Number('1.23e+2').toExponential()", js_str!("1.23e+2")),
     ]);
 }
 
 #[test]
 fn to_fixed() {
     run_test_actions([
-        TestAction::assert_eq("Number().toFixed()", js_string!("0")),
-        TestAction::assert_eq("Number('3.456e+4').toFixed()", js_string!("34560")),
-        TestAction::assert_eq("Number('3.456e-4').toFixed()", js_string!("0")),
-        TestAction::assert_eq("Number(5).toFixed()", js_string!("5")),
-        TestAction::assert_eq(
-            "Number('I am also not a number').toFixed()",
-            js_string!("NaN"),
-        ),
-        TestAction::assert_eq("(1.35).toFixed(1)", js_string!("1.4")),
+        TestAction::assert_eq("Number().toFixed()", js_str!("0")),
+        TestAction::assert_eq("Number('3.456e+4').toFixed()", js_str!("34560")),
+        TestAction::assert_eq("Number('3.456e-4').toFixed()", js_str!("0")),
+        TestAction::assert_eq("Number(5).toFixed()", js_str!("5")),
+        TestAction::assert_eq("Number('I am also not a number').toFixed()", js_str!("NaN")),
+        TestAction::assert_eq("(1.35).toFixed(1)", js_str!("1.4")),
         // Test cases from https://source.chromium.org/chromium/chromium/src/+/main:v8/test/mjsunit/number-tostring-func.js;l=157-240;drc=aa3518a0f37245ebe8f062dce97ee492e2a41652
-        TestAction::assert_eq("(NaN).toFixed(2)", js_string!("NaN")),
-        TestAction::assert_eq("(1/0).toFixed(2)", js_string!("Infinity")),
-        TestAction::assert_eq("(-1/0).toFixed(2)", js_string!("-Infinity")),
+        TestAction::assert_eq("(NaN).toFixed(2)", js_str!("NaN")),
+        TestAction::assert_eq("(1/0).toFixed(2)", js_str!("Infinity")),
+        TestAction::assert_eq("(-1/0).toFixed(2)", js_str!("-Infinity")),
         TestAction::assert_eq(
             "(1111111111111111111111).toFixed(8)",
-            js_string!("1.1111111111111111e+21"),
-        ),
-        TestAction::assert_eq("(0.1).toFixed(1)", js_string!("0.1")),
-        TestAction::assert_eq("(0.1).toFixed(2)", js_string!("0.10")),
-        TestAction::assert_eq("(0.1).toFixed(3)", js_string!("0.100")),
-        TestAction::assert_eq("(0.01).toFixed(2)", js_string!("0.01")),
-        TestAction::assert_eq("(0.01).toFixed(3)", js_string!("0.010")),
-        TestAction::assert_eq("(0.01).toFixed(4)", js_string!("0.0100")),
-        TestAction::assert_eq("(0.001).toFixed(2)", js_string!("0.00")),
-        TestAction::assert_eq("(0.001).toFixed(3)", js_string!("0.001")),
-        TestAction::assert_eq("(0.001).toFixed(4)", js_string!("0.0010")),
-        TestAction::assert_eq("(1).toFixed(4)", js_string!("1.0000")),
-        TestAction::assert_eq("(1).toFixed(1)", js_string!("1.0")),
-        TestAction::assert_eq("(1).toFixed(0)", js_string!("1")),
-        TestAction::assert_eq("(12).toFixed(0)", js_string!("12")),
-        TestAction::assert_eq("(1.1).toFixed(0)", js_string!("1")),
-        TestAction::assert_eq("(12.1).toFixed(0)", js_string!("12")),
-        TestAction::assert_eq("(1.12).toFixed(0)", js_string!("1")),
-        TestAction::assert_eq("(12.12).toFixed(0)", js_string!("12")),
-        TestAction::assert_eq("(0.0000006).toFixed(7)", js_string!("0.0000006")),
-        TestAction::assert_eq("(0.00000006).toFixed(8)", js_string!("0.00000006")),
-        TestAction::assert_eq("(0.00000006).toFixed(9)", js_string!("0.000000060")),
-        TestAction::assert_eq("(0.00000006).toFixed(10)", js_string!("0.0000000600")),
-        TestAction::assert_eq("(0).toFixed(0)", js_string!("0")),
-        TestAction::assert_eq("(0).toFixed(1)", js_string!("0.0")),
-        TestAction::assert_eq("(0).toFixed(2)", js_string!("0.00")),
+            js_str!("1.1111111111111111e+21"),
+        ),
+        TestAction::assert_eq("(0.1).toFixed(1)", js_str!("0.1")),
+        TestAction::assert_eq("(0.1).toFixed(2)", js_str!("0.10")),
+        TestAction::assert_eq("(0.1).toFixed(3)", js_str!("0.100")),
+        TestAction::assert_eq("(0.01).toFixed(2)", js_str!("0.01")),
+        TestAction::assert_eq("(0.01).toFixed(3)", js_str!("0.010")),
+        TestAction::assert_eq("(0.01).toFixed(4)", js_str!("0.0100")),
+        TestAction::assert_eq("(0.001).toFixed(2)", js_str!("0.00")),
+        TestAction::assert_eq("(0.001).toFixed(3)", js_str!("0.001")),
+        TestAction::assert_eq("(0.001).toFixed(4)", js_str!("0.0010")),
+        TestAction::assert_eq("(1).toFixed(4)", js_str!("1.0000")),
+        TestAction::assert_eq("(1).toFixed(1)", js_str!("1.0")),
+        TestAction::assert_eq("(1).toFixed(0)", js_str!("1")),
+        TestAction::assert_eq("(12).toFixed(0)", js_str!("12")),
+        TestAction::assert_eq("(1.1).toFixed(0)", js_str!("1")),
+        TestAction::assert_eq("(12.1).toFixed(0)", js_str!("12")),
+        TestAction::assert_eq("(1.12).toFixed(0)", js_str!("1")),
+        TestAction::assert_eq("(12.12).toFixed(0)", js_str!("12")),
+        TestAction::assert_eq("(0.0000006).toFixed(7)", js_str!("0.0000006")),
+        TestAction::assert_eq("(0.00000006).toFixed(8)", js_str!("0.00000006")),
+        TestAction::assert_eq("(0.00000006).toFixed(9)", js_str!("0.000000060")),
+        TestAction::assert_eq("(0.00000006).toFixed(10)", js_str!("0.0000000600")),
+        TestAction::assert_eq("(0).toFixed(0)", js_str!("0")),
+        TestAction::assert_eq("(0).toFixed(1)", js_str!("0.0")),
+        TestAction::assert_eq("(0).toFixed(2)", js_str!("0.00")),
         TestAction::assert_eq(
             "(-1111111111111111111111).toFixed(8)",
-            js_string!("-1.1111111111111111e+21"),
-        ),
-        TestAction::assert_eq("(-0.1).toFixed(1)", js_string!("-0.1")),
-        TestAction::assert_eq("(-0.1).toFixed(2)", js_string!("-0.10")),
-        TestAction::assert_eq("(-0.1).toFixed(3)", js_string!("-0.100")),
-        TestAction::assert_eq("(-0.01).toFixed(2)", js_string!("-0.01")),
-        TestAction::assert_eq("(-0.01).toFixed(3)", js_string!("-0.010")),
-        TestAction::assert_eq("(-0.01).toFixed(4)", js_string!("-0.0100")),
-        TestAction::assert_eq("(-0.001).toFixed(2)", js_string!("-0.00")),
-        TestAction::assert_eq("(-0.001).toFixed(3)", js_string!("-0.001")),
-        TestAction::assert_eq("(-0.001).toFixed(4)", js_string!("-0.0010")),
-        TestAction::assert_eq("(-1).toFixed(4)", js_string!("-1.0000")),
-        TestAction::assert_eq("(-1).toFixed(1)", js_string!("-1.0")),
-        TestAction::assert_eq("(-1).toFixed(0)", js_string!("-1")),
-        TestAction::assert_eq("(-1.1).toFixed(0)", js_string!("-1")),
-        TestAction::assert_eq("(-12.1).toFixed(0)", js_string!("-12")),
-        TestAction::assert_eq("(-1.12).toFixed(0)", js_string!("-1")),
-        TestAction::assert_eq("(-12.12).toFixed(0)", js_string!("-12")),
-        TestAction::assert_eq("(-0.0000006).toFixed(7)", js_string!("-0.0000006")),
-        TestAction::assert_eq("(-0.00000006).toFixed(8)", js_string!("-0.00000006")),
-        TestAction::assert_eq("(-0.00000006).toFixed(9)", js_string!("-0.000000060")),
-        TestAction::assert_eq("(-0.00000006).toFixed(10)", js_string!("-0.0000000600")),
-        TestAction::assert_eq("(-0).toFixed(0)", js_string!("0")),
-        TestAction::assert_eq("(-0).toFixed(1)", js_string!("0.0")),
-        TestAction::assert_eq("(-0).toFixed(2)", js_string!("0.00")),
-        TestAction::assert_eq("(0.00001).toFixed(5)", js_string!("0.00001")),
+            js_str!("-1.1111111111111111e+21"),
+        ),
+        TestAction::assert_eq("(-0.1).toFixed(1)", js_str!("-0.1")),
+        TestAction::assert_eq("(-0.1).toFixed(2)", js_str!("-0.10")),
+        TestAction::assert_eq("(-0.1).toFixed(3)", js_str!("-0.100")),
+        TestAction::assert_eq("(-0.01).toFixed(2)", js_str!("-0.01")),
+        TestAction::assert_eq("(-0.01).toFixed(3)", js_str!("-0.010")),
+        TestAction::assert_eq("(-0.01).toFixed(4)", js_str!("-0.0100")),
+        TestAction::assert_eq("(-0.001).toFixed(2)", js_str!("-0.00")),
+        TestAction::assert_eq("(-0.001).toFixed(3)", js_str!("-0.001")),
+        TestAction::assert_eq("(-0.001).toFixed(4)", js_str!("-0.0010")),
+        TestAction::assert_eq("(-1).toFixed(4)", js_str!("-1.0000")),
+        TestAction::assert_eq("(-1).toFixed(1)", js_str!("-1.0")),
+        TestAction::assert_eq("(-1).toFixed(0)", js_str!("-1")),
+        TestAction::assert_eq("(-1.1).toFixed(0)", js_str!("-1")),
+        TestAction::assert_eq("(-12.1).toFixed(0)", js_str!("-12")),
+        TestAction::assert_eq("(-1.12).toFixed(0)", js_str!("-1")),
+        TestAction::assert_eq("(-12.12).toFixed(0)", js_str!("-12")),
+        TestAction::assert_eq("(-0.0000006).toFixed(7)", js_str!("-0.0000006")),
+        TestAction::assert_eq("(-0.00000006).toFixed(8)", js_str!("-0.00000006")),
+        TestAction::assert_eq("(-0.00000006).toFixed(9)", js_str!("-0.000000060")),
+        TestAction::assert_eq("(-0.00000006).toFixed(10)", js_str!("-0.0000000600")),
+        TestAction::assert_eq("(-0).toFixed(0)", js_str!("0")),
+        TestAction::assert_eq("(-0).toFixed(1)", js_str!("0.0")),
+        TestAction::assert_eq("(-0).toFixed(2)", js_str!("0.00")),
+        TestAction::assert_eq("(0.00001).toFixed(5)", js_str!("0.00001")),
         TestAction::assert_eq(
             "(0.0000000000000000001).toFixed(20)",
-            js_string!("0.00000000000000000010"),
+            js_str!("0.00000000000000000010"),
         ),
-        TestAction::assert_eq("(0.00001).toFixed(17)", js_string!("0.00001000000000000")),
-        TestAction::assert_eq("(1).toFixed(17)", js_string!("1.00000000000000000")),
+        TestAction::assert_eq("(0.00001).toFixed(17)", js_str!("0.00001000000000000")),
+        TestAction::assert_eq("(1).toFixed(17)", js_str!("1.00000000000000000")),
         TestAction::assert_eq(
             "(100000000000000128).toFixed(1)",
-            js_string!("100000000000000128.0"),
+            js_str!("100000000000000128.0"),
         ),
         TestAction::assert_eq(
             "(10000000000000128).toFixed(2)",
-            js_string!("10000000000000128.00"),
+            js_str!("10000000000000128.00"),
         ),
         TestAction::assert_eq(
             "(10000000000000128).toFixed(20)",
-            js_string!("10000000000000128.00000000000000000000"),
+            js_str!("10000000000000128.00000000000000000000"),
         ),
-        TestAction::assert_eq("(-42).toFixed(3)", js_string!("-42.000")),
+        TestAction::assert_eq("(-42).toFixed(3)", js_str!("-42.000")),
         TestAction::assert_eq(
             "(-0.0000000000000000001).toFixed(20)",
-            js_string!("-0.00000000000000000010"),
+            js_str!("-0.00000000000000000010"),
         ),
         TestAction::assert_eq(
             "(0.123123123123123).toFixed(20)",
-            js_string!("0.12312312312312299889"),
+            js_str!("0.12312312312312299889"),
         ),
         TestAction::assert_eq(
             "(-1000000000000000128).toFixed()",
-            js_string!("-1000000000000000128"),
+            js_str!("-1000000000000000128"),
         ),
-        TestAction::assert_eq("(0).toFixed()", js_string!("0")),
+        TestAction::assert_eq("(0).toFixed()", js_str!("0")),
         TestAction::assert_eq(
             "(1000000000000000128).toFixed()",
-            js_string!("1000000000000000128"),
+            js_str!("1000000000000000128"),
         ),
-        TestAction::assert_eq("(1000).toFixed()", js_string!("1000")),
-        TestAction::assert_eq("(0.00001).toFixed()", js_string!("0")),
+        TestAction::assert_eq("(1000).toFixed()", js_str!("1000")),
+        TestAction::assert_eq("(0.00001).toFixed()", js_str!("0")),
         // Test that we round up even when the last digit generated is even.
         // dtoa does not do this in its original form.
-        TestAction::assert_eq("(0.5).toFixed(0)", js_string!("1")),
-        TestAction::assert_eq("(-0.5).toFixed(0)", js_string!("-1")),
-        TestAction::assert_eq("(1.25).toFixed(1)", js_string!("1.3")),
+        TestAction::assert_eq("(0.5).toFixed(0)", js_str!("1")),
+        TestAction::assert_eq("(-0.5).toFixed(0)", js_str!("-1")),
+        TestAction::assert_eq("(1.25).toFixed(1)", js_str!("1.3")),
         // This is bizare, but Spidermonkey and KJS behave the same.
-        TestAction::assert_eq("(234.2040).toFixed(4)", js_string!("234.2040")),
-        TestAction::assert_eq("(234.2040506).toFixed(4)", js_string!("234.2041")),
+        TestAction::assert_eq("(234.2040).toFixed(4)", js_str!("234.2040")),
+        TestAction::assert_eq("(234.2040506).toFixed(4)", js_str!("234.2041")),
     ]);
 }
 
@@ -162,8 +160,8 @@ fn to_fixed() {
 #[test]
 fn issue_2609() {
     run_test_actions([
-        TestAction::assert_eq("(1.25).toFixed(1)", js_string!("1.3")),
-        TestAction::assert_eq("(1.35).toFixed(1)", js_string!("1.4")),
+        TestAction::assert_eq("(1.25).toFixed(1)", js_str!("1.3")),
+        TestAction::assert_eq("(1.35).toFixed(1)", js_str!("1.4")),
     ]);
 }
 
@@ -172,10 +170,10 @@ fn to_locale_string() {
     // TODO: We don't actually do any locale checking here
     // To honor the spec we should print numbers according to user locale.
     run_test_actions([
-        TestAction::assert_eq("Number().toLocaleString()", js_string!("0")),
-        TestAction::assert_eq("Number(5).toLocaleString()", js_string!("5")),
-        TestAction::assert_eq("Number('345600').toLocaleString()", js_string!("345600")),
-        TestAction::assert_eq("Number(-25).toLocaleString()", js_string!("-25")),
+        TestAction::assert_eq("Number().toLocaleString()", js_str!("0")),
+        TestAction::assert_eq("Number(5).toLocaleString()", js_str!("5")),
+        TestAction::assert_eq("Number('345600').toLocaleString()", js_str!("345600")),
+        TestAction::assert_eq("Number(-25).toLocaleString()", js_str!("-25")),
     ]);
 }
 
@@ -183,21 +181,21 @@ fn to_locale_string() {
 fn to_precision() {
     const ERROR: &str = "precision must be an integer at least 1 and no greater than 100";
     run_test_actions([
-        TestAction::assert_eq("(1/0).toPrecision(3)", js_string!("Infinity")),
-        TestAction::assert_eq("Number().toPrecision()", js_string!("0")),
-        TestAction::assert_eq("Number().toPrecision(undefined)", js_string!("0")),
-        TestAction::assert_eq("(123456789).toPrecision(1)", js_string!("1e+8")),
-        TestAction::assert_eq("(123456789).toPrecision(4)", js_string!("1.235e+8")),
-        TestAction::assert_eq("(123456789).toPrecision(9)", js_string!("123456789")),
-        TestAction::assert_eq("(-123456789).toPrecision(4)", js_string!("-1.235e+8")),
+        TestAction::assert_eq("(1/0).toPrecision(3)", js_str!("Infinity")),
+        TestAction::assert_eq("Number().toPrecision()", js_str!("0")),
+        TestAction::assert_eq("Number().toPrecision(undefined)", js_str!("0")),
+        TestAction::assert_eq("(123456789).toPrecision(1)", js_str!("1e+8")),
+        TestAction::assert_eq("(123456789).toPrecision(4)", js_str!("1.235e+8")),
+        TestAction::assert_eq("(123456789).toPrecision(9)", js_str!("123456789")),
+        TestAction::assert_eq("(-123456789).toPrecision(4)", js_str!("-1.235e+8")),
         TestAction::assert_eq(
             "(123456789).toPrecision(50)",
-            js_string!("123456789.00000000000000000000000000000000000000000"),
+            js_str!("123456789.00000000000000000000000000000000000000000"),
         ),
-        TestAction::assert_eq("(0.1).toPrecision(4)", js_string!("0.1000")),
+        TestAction::assert_eq("(0.1).toPrecision(4)", js_str!("0.1000")),
         TestAction::assert_eq(
             "(1/3).toPrecision(60)",
-            js_string!("0.333333333333333314829616256247390992939472198486328125000000"),
+            js_str!("0.333333333333333314829616256247390992939472198486328125000000"),
         ),
         TestAction::assert_native_error("(1).toPrecision(101)", JsNativeErrorKind::Range, ERROR),
         TestAction::assert_native_error("(1).toPrecision(0)", JsNativeErrorKind::Range, ERROR),
@@ -209,132 +207,126 @@ fn to_precision() {
 #[test]
 fn to_string() {
     run_test_actions([
-        TestAction::assert_eq("Number(NaN).toString()", js_string!("NaN")),
-        TestAction::assert_eq("Number(1/0).toString()", js_string!("Infinity")),
-        TestAction::assert_eq("Number(-1/0).toString()", js_string!("-Infinity")),
-        TestAction::assert_eq("Number(0).toString()", js_string!("0")),
-        TestAction::assert_eq("Number(9).toString()", js_string!("9")),
-        TestAction::assert_eq("Number(90).toString()", js_string!("90")),
-        TestAction::assert_eq("Number(90.12).toString()", js_string!("90.12")),
-        TestAction::assert_eq("Number(0.1).toString()", js_string!("0.1")),
-        TestAction::assert_eq("Number(0.01).toString()", js_string!("0.01")),
-        TestAction::assert_eq("Number(0.0123).toString()", js_string!("0.0123")),
-        TestAction::assert_eq("Number(0.00001).toString()", js_string!("0.00001")),
-        TestAction::assert_eq("Number(0.000001).toString()", js_string!("0.000001")),
-        TestAction::assert_eq("Number(NaN).toString(16)", js_string!("NaN")),
-        TestAction::assert_eq("Number(1/0).toString(16)", js_string!("Infinity")),
-        TestAction::assert_eq("Number(-1/0).toString(16)", js_string!("-Infinity")),
-        TestAction::assert_eq("Number(0).toString(16)", js_string!("0")),
-        TestAction::assert_eq("Number(9).toString(16)", js_string!("9")),
-        TestAction::assert_eq("Number(90).toString(16)", js_string!("5a")),
-        TestAction::assert_eq("Number(90.12).toString(16)", js_string!("5a.1eb851eb852")),
-        TestAction::assert_eq("Number(0.1).toString(16)", js_string!("0.1999999999999a")),
-        TestAction::assert_eq("Number(0.01).toString(16)", js_string!("0.028f5c28f5c28f6")),
-        TestAction::assert_eq(
-            "Number(0.0123).toString(16)",
-            js_string!("0.032617c1bda511a"),
-        ),
+        TestAction::assert_eq("Number(NaN).toString()", js_str!("NaN")),
+        TestAction::assert_eq("Number(1/0).toString()", js_str!("Infinity")),
+        TestAction::assert_eq("Number(-1/0).toString()", js_str!("-Infinity")),
+        TestAction::assert_eq("Number(0).toString()", js_str!("0")),
+        TestAction::assert_eq("Number(9).toString()", js_str!("9")),
+        TestAction::assert_eq("Number(90).toString()", js_str!("90")),
+        TestAction::assert_eq("Number(90.12).toString()", js_str!("90.12")),
+        TestAction::assert_eq("Number(0.1).toString()", js_str!("0.1")),
+        TestAction::assert_eq("Number(0.01).toString()", js_str!("0.01")),
+        TestAction::assert_eq("Number(0.0123).toString()", js_str!("0.0123")),
+        TestAction::assert_eq("Number(0.00001).toString()", js_str!("0.00001")),
+        TestAction::assert_eq("Number(0.000001).toString()", js_str!("0.000001")),
+        TestAction::assert_eq("Number(NaN).toString(16)", js_str!("NaN")),
+        TestAction::assert_eq("Number(1/0).toString(16)", js_str!("Infinity")),
+        TestAction::assert_eq("Number(-1/0).toString(16)", js_str!("-Infinity")),
+        TestAction::assert_eq("Number(0).toString(16)", js_str!("0")),
+        TestAction::assert_eq("Number(9).toString(16)", js_str!("9")),
+        TestAction::assert_eq("Number(90).toString(16)", js_str!("5a")),
+        TestAction::assert_eq("Number(90.12).toString(16)", js_str!("5a.1eb851eb852")),
+        TestAction::assert_eq("Number(0.1).toString(16)", js_str!("0.1999999999999a")),
+        TestAction::assert_eq("Number(0.01).toString(16)", js_str!("0.028f5c28f5c28f6")),
+        TestAction::assert_eq("Number(0.0123).toString(16)", js_str!("0.032617c1bda511a")),
         TestAction::assert_eq(
             "Number(111111111111111111111).toString(16)",
-            js_string!("605f9f6dd18bc8000"),
+            js_str!("605f9f6dd18bc8000"),
         ),
         TestAction::assert_eq(
             "Number(1111111111111111111111).toString(16)",
-            js_string!("3c3bc3a4a2f75c0000"),
+            js_str!("3c3bc3a4a2f75c0000"),
         ),
         TestAction::assert_eq(
             "Number(11111111111111111111111).toString(16)",
-            js_string!("25a55a46e5da9a00000"),
+            js_str!("25a55a46e5da9a00000"),
         ),
         TestAction::assert_eq(
             "Number(0.00001).toString(16)",
-            js_string!("0.0000a7c5ac471b4788"),
+            js_str!("0.0000a7c5ac471b4788"),
         ),
         TestAction::assert_eq(
             "Number(0.000001).toString(16)",
-            js_string!("0.000010c6f7a0b5ed8d"),
+            js_str!("0.000010c6f7a0b5ed8d"),
         ),
         TestAction::assert_eq(
             "Number(0.0000001).toString(16)",
-            js_string!("0.000001ad7f29abcaf48"),
+            js_str!("0.000001ad7f29abcaf48"),
         ),
         TestAction::assert_eq(
             "Number(0.00000012).toString(16)",
-            js_string!("0.000002036565348d256"),
+            js_str!("0.000002036565348d256"),
         ),
         TestAction::assert_eq(
             "Number(0.000000123).toString(16)",
-            js_string!("0.0000021047ee22aa466"),
+            js_str!("0.0000021047ee22aa466"),
         ),
         TestAction::assert_eq(
             "Number(0.00000001).toString(16)",
-            js_string!("0.0000002af31dc4611874"),
+            js_str!("0.0000002af31dc4611874"),
         ),
         TestAction::assert_eq(
             "Number(0.000000012).toString(16)",
-            js_string!("0.000000338a23b87483be"),
+            js_str!("0.000000338a23b87483be"),
         ),
         TestAction::assert_eq(
             "Number(0.0000000123).toString(16)",
-            js_string!("0.00000034d3fe36aaa0a2"),
+            js_str!("0.00000034d3fe36aaa0a2"),
         ),
-        TestAction::assert_eq("Number(-0).toString(16)", js_string!("0")),
-        TestAction::assert_eq("Number(-9).toString(16)", js_string!("-9")),
+        TestAction::assert_eq("Number(-0).toString(16)", js_str!("0")),
+        TestAction::assert_eq("Number(-9).toString(16)", js_str!("-9")),
         //
-        TestAction::assert_eq("Number(-90).toString(16)", js_string!("-5a")),
-        TestAction::assert_eq("Number(-90.12).toString(16)", js_string!("-5a.1eb851eb852")),
-        TestAction::assert_eq("Number(-0.1).toString(16)", js_string!("-0.1999999999999a")),
-        TestAction::assert_eq(
-            "Number(-0.01).toString(16)",
-            js_string!("-0.028f5c28f5c28f6"),
-        ),
+        TestAction::assert_eq("Number(-90).toString(16)", js_str!("-5a")),
+        TestAction::assert_eq("Number(-90.12).toString(16)", js_str!("-5a.1eb851eb852")),
+        TestAction::assert_eq("Number(-0.1).toString(16)", js_str!("-0.1999999999999a")),
+        TestAction::assert_eq("Number(-0.01).toString(16)", js_str!("-0.028f5c28f5c28f6")),
         TestAction::assert_eq(
             "Number(-0.0123).toString(16)",
-            js_string!("-0.032617c1bda511a"),
+            js_str!("-0.032617c1bda511a"),
         ),
         TestAction::assert_eq(
             "Number(-111111111111111111111).toString(16)",
-            js_string!("-605f9f6dd18bc8000"),
+            js_str!("-605f9f6dd18bc8000"),
         ),
         TestAction::assert_eq(
             "Number(-1111111111111111111111).toString(16)",
-            js_string!("-3c3bc3a4a2f75c0000"),
+            js_str!("-3c3bc3a4a2f75c0000"),
         ),
         TestAction::assert_eq(
             "Number(-11111111111111111111111).toString(16)",
-            js_string!("-25a55a46e5da9a00000"),
+            js_str!("-25a55a46e5da9a00000"),
         ),
         TestAction::assert_eq(
             "Number(-0.00001).toString(16)",
-            js_string!("-0.0000a7c5ac471b4788"),
+            js_str!("-0.0000a7c5ac471b4788"),
         ),
         TestAction::assert_eq(
             "Number(-0.000001).toString(16)",
-            js_string!("-0.000010c6f7a0b5ed8d"),
+            js_str!("-0.000010c6f7a0b5ed8d"),
         ),
         TestAction::assert_eq(
             "Number(-0.0000001).toString(16)",
-            js_string!("-0.000001ad7f29abcaf48"),
+            js_str!("-0.000001ad7f29abcaf48"),
         ),
         TestAction::assert_eq(
             "Number(-0.00000012).toString(16)",
-            js_string!("-0.000002036565348d256"),
+            js_str!("-0.000002036565348d256"),
         ),
         TestAction::assert_eq(
             "Number(-0.000000123).toString(16)",
-            js_string!("-0.0000021047ee22aa466"),
+            js_str!("-0.0000021047ee22aa466"),
         ),
         TestAction::assert_eq(
             "Number(-0.00000001).toString(16)",
-            js_string!("-0.0000002af31dc4611874"),
+            js_str!("-0.0000002af31dc4611874"),
         ),
         TestAction::assert_eq(
             "Number(-0.000000012).toString(16)",
-            js_string!("-0.000000338a23b87483be"),
+            js_str!("-0.000000338a23b87483be"),
         ),
         TestAction::assert_eq(
             "Number(-0.0000000123).toString(16)",
-            js_string!("-0.00000034d3fe36aaa0a2"),
+            js_str!("-0.00000034d3fe36aaa0a2"),
         ),
     ]);
 }
@@ -342,26 +334,26 @@ fn to_string() {
 #[test]
 fn num_to_string_exponential() {
     run_test_actions([
-        TestAction::assert_eq("(0).toString()", js_string!("0")),
-        TestAction::assert_eq("(-0).toString()", js_string!("0")),
+        TestAction::assert_eq("(0).toString()", js_str!("0")),
+        TestAction::assert_eq("(-0).toString()", js_str!("0")),
         TestAction::assert_eq(
             "(111111111111111111111).toString()",
-            js_string!("111111111111111110000"),
+            js_str!("111111111111111110000"),
         ),
         TestAction::assert_eq(
             "(1111111111111111111111).toString()",
-            js_string!("1.1111111111111111e+21"),
+            js_str!("1.1111111111111111e+21"),
         ),
         TestAction::assert_eq(
             "(11111111111111111111111).toString()",
-            js_string!("1.1111111111111111e+22"),
-        ),
-        TestAction::assert_eq("(0.0000001).toString()", js_string!("1e-7")),
-        TestAction::assert_eq("(0.00000012).toString()", js_string!("1.2e-7")),
-        TestAction::assert_eq("(0.000000123).toString()", js_string!("1.23e-7")),
-        TestAction::assert_eq("(0.00000001).toString()", js_string!("1e-8")),
-        TestAction::assert_eq("(0.000000012).toString()", js_string!("1.2e-8")),
-        TestAction::assert_eq("(0.0000000123).toString()", js_string!("1.23e-8")),
+            js_str!("1.1111111111111111e+22"),
+        ),
+        TestAction::assert_eq("(0.0000001).toString()", js_str!("1e-7")),
+        TestAction::assert_eq("(0.00000012).toString()", js_str!("1.2e-7")),
+        TestAction::assert_eq("(0.000000123).toString()", js_str!("1.23e-7")),
+        TestAction::assert_eq("(0.00000001).toString()", js_str!("1e-8")),
+        TestAction::assert_eq("(0.000000012).toString()", js_str!("1.2e-8")),
+        TestAction::assert_eq("(0.0000000123).toString()", js_str!("1.23e-8")),
     ]);
 }
 
@@ -642,11 +634,11 @@ fn issue_2717() {
     run_test_actions([
         TestAction::assert_eq(
             "(0.1600057092765239).toString(36)",
-            js_string!("0.5rd85dm1ixq"),
+            js_str!("0.5rd85dm1ixq"),
         ),
         TestAction::assert_eq(
             "(0.23046743672210102).toString(36)",
-            js_string!("0.8aoosla2phj"),
+            js_str!("0.8aoosla2phj"),
         ),
     ]);
 }

core/engine/src/builtins/object/mod.rs

@@ -13,8 +13,6 @@
 //! [spec]: https://tc39.es/ecma262/#sec-objects
 //! [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object
 
-use std::ops::Deref;
-
 use super::{
     error::ErrorObject, Array, BuiltInBuilder, BuiltInConstructor, Date, IntrinsicObject, RegExp,
 };
@@ -30,12 +28,13 @@ use crate::{
     },
     property::{Attribute, PropertyDescriptor, PropertyKey, PropertyNameKind},
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     symbol::JsSymbol,
     value::JsValue,
     Context, JsArgs, JsData, JsResult, JsString,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use tap::{Conv, Pipe};
 
@@ -63,7 +62,7 @@ impl IntrinsicObject for OrdinaryObject {
         BuiltInBuilder::from_standard_constructor::<Self>(realm)
             .inherits(None)
             .accessor(
-                utf16!("__proto__"),
+                js_string!("__proto__"),
                 Some(legacy_proto_getter),
                 Some(legacy_setter_proto),
                 Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
@@ -574,42 +573,42 @@ impl OrdinaryObject {
         // 4. If Desc has a [[Value]] field, then
         if let Some(value) = desc.value() {
             // a. Perform ! CreateDataPropertyOrThrow(obj, "value", Desc.[[Value]]).
-            obj.create_data_property_or_throw(utf16!("value"), value.clone(), context)
+            obj.create_data_property_or_throw(js_str!("value"), value.clone(), context)
                 .expect("CreateDataPropertyOrThrow cannot fail here");
         }
 
         // 5. If Desc has a [[Writable]] field, then
         if let Some(writable) = desc.writable() {
             // a. Perform ! CreateDataPropertyOrThrow(obj, "writable", Desc.[[Writable]]).
-            obj.create_data_property_or_throw(utf16!("writable"), writable, context)
+            obj.create_data_property_or_throw(js_str!("writable"), writable, context)
                 .expect("CreateDataPropertyOrThrow cannot fail here");
         }
 
         // 6. If Desc has a [[Get]] field, then
         if let Some(get) = desc.get() {
             // a. Perform ! CreateDataPropertyOrThrow(obj, "get", Desc.[[Get]]).
-            obj.create_data_property_or_throw(utf16!("get"), get.clone(), context)
+            obj.create_data_property_or_throw(js_str!("get"), get.clone(), context)
                 .expect("CreateDataPropertyOrThrow cannot fail here");
         }
 
         // 7. If Desc has a [[Set]] field, then
         if let Some(set) = desc.set() {
             // a. Perform ! CreateDataPropertyOrThrow(obj, "set", Desc.[[Set]]).
-            obj.create_data_property_or_throw(utf16!("set"), set.clone(), context)
+            obj.create_data_property_or_throw(js_str!("set"), set.clone(), context)
                 .expect("CreateDataPropertyOrThrow cannot fail here");
         }
 
         // 8. If Desc has an [[Enumerable]] field, then
         if let Some(enumerable) = desc.enumerable() {
             // a. Perform ! CreateDataPropertyOrThrow(obj, "enumerable", Desc.[[Enumerable]]).
-            obj.create_data_property_or_throw(utf16!("enumerable"), enumerable, context)
+            obj.create_data_property_or_throw(js_str!("enumerable"), enumerable, context)
                 .expect("CreateDataPropertyOrThrow cannot fail here");
         }
 
         // 9. If Desc has a [[Configurable]] field, then
         if let Some(configurable) = desc.configurable() {
             // a. Perform ! CreateDataPropertyOrThrow(obj, "configurable", Desc.[[Configurable]]).
-            obj.create_data_property_or_throw(utf16!("configurable"), configurable, context)
+            obj.create_data_property_or_throw(js_str!("configurable"), configurable, context)
                 .expect("CreateDataPropertyOrThrow cannot fail here");
         }
 
@@ -825,11 +824,11 @@ impl OrdinaryObject {
     pub fn to_string(this: &JsValue, _: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
         // 1. If the this value is undefined, return "[object Undefined]".
         if this.is_undefined() {
-            return Ok(js_string!("[object Undefined]").into());
+            return Ok(js_str!("[object Undefined]").into());
         }
         // 2. If the this value is null, return "[object Null]".
         if this.is_null() {
-            return Ok(js_string!("[object Null]").into());
+            return Ok(js_str!("[object Null]").into());
         }
         // 3. Let O be ! ToObject(this value).
         let o = this.to_object(context).expect("toObject cannot fail here");
@@ -837,37 +836,37 @@ impl OrdinaryObject {
         //  4. Let isArray be ? IsArray(O).
         //  5. If isArray is true, let builtinTag be "Array".
         let builtin_tag = if o.is_array_abstract()? {
-            utf16!("Array")
+            js_str!("Array")
         } else {
             let o_borrow = o.borrow();
 
             if o_borrow.is_arguments() {
                 // 6. Else if O has a [[ParameterMap]] internal slot, let builtinTag be "Arguments".
-                utf16!("Arguments")
+                js_str!("Arguments")
             } else if o.is_callable() {
                 // 7. Else if O has a [[Call]] internal method, let builtinTag be "Function".
-                utf16!("Function")
+                js_str!("Function")
             } else if o.is::<ErrorObject>() {
                 // 8. Else if O has an [[ErrorData]] internal slot, let builtinTag be "Error".
-                utf16!("Error")
+                js_str!("Error")
             } else if o.is::<bool>() {
                 // 9. Else if O has a [[BooleanData]] internal slot, let builtinTag be "Boolean".
-                utf16!("Boolean")
+                js_str!("Boolean")
             } else if o.is::<f64>() {
                 // 10. Else if O has a [[NumberData]] internal slot, let builtinTag be "Number".
-                utf16!("Number")
+                js_str!("Number")
             } else if o.is::<JsString>() {
                 // 11. Else if O has a [[StringData]] internal slot, let builtinTag be "String".
-                utf16!("String")
+                js_str!("String")
             } else if o.is::<Date>() {
                 // 12. Else if O has a [[DateValue]] internal slot, let builtinTag be "Date".
-                utf16!("Date")
+                js_str!("Date")
             } else if o.is::<RegExp>() {
                 // 13. Else if O has a [[RegExpMatcher]] internal slot, let builtinTag be "RegExp".
-                utf16!("RegExp")
+                js_str!("RegExp")
             } else {
                 // 14. Else, let builtinTag be "Object".
-                utf16!("Object")
+                js_str!("Object")
             }
         };
 
@@ -875,10 +874,10 @@ impl OrdinaryObject {
         let tag = o.get(JsSymbol::to_string_tag(), context)?;
 
         // 16. If Type(tag) is not String, set tag to builtinTag.
-        let tag_str = tag.as_string().map_or(builtin_tag, JsString::deref);
+        let tag_str = tag.as_string().map_or(builtin_tag, JsString::as_str);
 
         // 17. Return the string-concatenation of "[object ", tag, and "]".
-        Ok(js_string!(utf16!("[object "), tag_str, utf16!("]")).into())
+        Ok(js_string!(js_str!("[object "), tag_str, js_str!("]")).into())
     }
 
     /// `Object.prototype.toLocaleString( [ reserved1 [ , reserved2 ] ] )`
@@ -897,7 +896,7 @@ impl OrdinaryObject {
     ) -> JsResult<JsValue> {
         // 1. Let O be the this value.
         // 2. Return ? Invoke(O, "toString").
-        this.invoke(utf16!("toString"), &[], context)
+        this.invoke(js_str!("toString"), &[], context)
     }
 
     /// `Object.prototype.hasOwnProperty( property )`

core/engine/src/builtins/object/tests.rs

@@ -1,4 +1,5 @@
-use crate::{js_string, run_test_actions, JsNativeErrorKind, JsValue, TestAction};
+use crate::{run_test_actions, JsNativeErrorKind, JsValue, TestAction};
+use boa_macros::js_str;
 use indoc::indoc;
 
 #[test]
@@ -137,21 +138,21 @@ fn object_to_string() {
             "#}),
         TestAction::assert_eq(
             "Object.prototype.toString.call(undefined)",
-            js_string!("[object Undefined]"),
+            js_str!("[object Undefined]"),
         ),
         TestAction::assert_eq(
             "Object.prototype.toString.call(null)",
-            js_string!("[object Null]"),
+            js_str!("[object Null]"),
         ),
-        TestAction::assert_eq("[].toString()", js_string!("[object Array]")),
-        TestAction::assert_eq("(() => {}).toString()", js_string!("[object Function]")),
-        TestAction::assert_eq("(new Error('')).toString()", js_string!("[object Error]")),
-        TestAction::assert_eq("Boolean().toString()", js_string!("[object Boolean]")),
-        TestAction::assert_eq("Number(42).toString()", js_string!("[object Number]")),
-        TestAction::assert_eq("String('boa').toString()", js_string!("[object String]")),
-        TestAction::assert_eq("(new Date()).toString()", js_string!("[object Date]")),
-        TestAction::assert_eq("/boa/.toString()", js_string!("[object RegExp]")),
-        TestAction::assert_eq("({}).toString()", js_string!("[object Object]")),
+        TestAction::assert_eq("[].toString()", js_str!("[object Array]")),
+        TestAction::assert_eq("(() => {}).toString()", js_str!("[object Function]")),
+        TestAction::assert_eq("(new Error('')).toString()", js_str!("[object Error]")),
+        TestAction::assert_eq("Boolean().toString()", js_str!("[object Boolean]")),
+        TestAction::assert_eq("Number(42).toString()", js_str!("[object Number]")),
+        TestAction::assert_eq("String('boa').toString()", js_str!("[object String]")),
+        TestAction::assert_eq("(new Date()).toString()", js_str!("[object Date]")),
+        TestAction::assert_eq("/boa/.toString()", js_str!("[object RegExp]")),
+        TestAction::assert_eq("({}).toString()", js_str!("[object Object]")),
     ]);
 }
 
@@ -163,7 +164,7 @@ fn define_symbol_property() {
                 let sym = Symbol("key");
                 Object.defineProperty(obj, sym, { value: "val" });
             "#}),
-        TestAction::assert_eq("obj[sym]", js_string!("val")),
+        TestAction::assert_eq("obj[sym]", js_str!("val")),
     ]);
 }
 

core/engine/src/builtins/options.rs

@@ -2,7 +2,7 @@
 
 use std::{fmt, str::FromStr};
 
-use crate::{object::JsObject, Context, JsNativeError, JsResult, JsString, JsValue};
+use crate::{object::JsObject, string::JsStr, Context, JsNativeError, JsResult, JsString, JsValue};
 
 /// A type used as an option parameter for [`get_option`].
 pub(crate) trait OptionType: Sized {
@@ -50,7 +50,7 @@ where
 /// [spec]: https://tc39.es/ecma402/#sec-getoption
 pub(crate) fn get_option<T: OptionType>(
     options: &JsObject,
-    property: &[u16],
+    property: JsStr<'_>,
     context: &mut Context,
 ) -> JsResult<Option<T>> {
     // 1. Let value be ? Get(options, property).

core/engine/src/builtins/promise/mod.rs

@@ -17,13 +17,13 @@ use crate::{
     },
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     symbol::JsSymbol,
     value::JsValue,
     Context, JsArgs, JsError, JsResult, JsString,
 };
 use boa_gc::{custom_trace, Finalize, Gc, GcRefCell, Trace};
-use boa_macros::JsData;
+use boa_macros::{js_str, JsData};
 use boa_profiler::Profiler;
 use std::{cell::Cell, rc::Rc};
 use tap::{Conv, Pipe};
@@ -768,7 +768,7 @@ impl Promise {
 
             // s. Perform ? Invoke(nextPromise, "then", « onFulfilled, resultCapability.[[Reject]] »).
             next_promise.invoke(
-                utf16!("then"),
+                js_str!("then"),
                 &[
                     on_fulfilled.into(),
                     result_capability.functions.reject.clone().into(),
@@ -957,15 +957,15 @@ impl Promise {
 
                         // 10. Perform ! CreateDataPropertyOrThrow(obj, "status", "fulfilled").
                         obj.create_data_property_or_throw(
-                            utf16!("status"),
-                            js_string!("fulfilled"),
+                            js_str!("status"),
+                            js_str!("fulfilled"),
                             context,
                         )
                         .expect("cannot fail per spec");
 
                         // 11. Perform ! CreateDataPropertyOrThrow(obj, "value", x).
                         obj.create_data_property_or_throw(
-                            utf16!("value"),
+                            js_str!("value"),
                             args.get_or_undefined(0).clone(),
                             context,
                         )
@@ -1047,15 +1047,15 @@ impl Promise {
 
                         // 10. Perform ! CreateDataPropertyOrThrow(obj, "status", "rejected").
                         obj.create_data_property_or_throw(
-                            utf16!("status"),
-                            js_string!("rejected"),
+                            js_str!("status"),
+                            js_str!("rejected"),
                             context,
                         )
                         .expect("cannot fail per spec");
 
                         // 11. Perform ! CreateDataPropertyOrThrow(obj, "reason", x).
                         obj.create_data_property_or_throw(
-                            utf16!("reason"),
+                            js_str!("reason"),
                             args.get_or_undefined(0).clone(),
                             context,
                         )
@@ -1107,7 +1107,7 @@ impl Promise {
 
             // ab. Perform ? Invoke(nextPromise, "then", « onFulfilled, onRejected »).
             next_promise.invoke(
-                utf16!("then"),
+                js_str!("then"),
                 &[on_fulfilled.into(), on_rejected.into()],
                 context,
             )?;
@@ -1343,7 +1343,7 @@ impl Promise {
 
             // s. Perform ? Invoke(nextPromise, "then", « resultCapability.[[Resolve]], onRejected »).
             next_promise.invoke(
-                utf16!("then"),
+                js_str!("then"),
                 &[
                     result_capability.functions.resolve.clone().into(),
                     on_rejected.into(),
@@ -1466,7 +1466,7 @@ impl Promise {
 
             // i. Perform ? Invoke(nextPromise, "then", « resultCapability.[[Resolve]], resultCapability.[[Reject]] »).
             next_promise.invoke(
-                utf16!("then"),
+                js_str!("then"),
                 &[
                     result_capability.functions.resolve.clone().into(),
                     result_capability.functions.reject.clone().into(),
@@ -1621,7 +1621,7 @@ impl Promise {
         let promise = this;
         // 2. Return ? Invoke(promise, "then", « undefined, onRejected »).
         promise.invoke(
-            utf16!("then"),
+            js_str!("then"),
             &[JsValue::undefined(), on_rejected.clone()],
             context,
         )
@@ -1667,7 +1667,7 @@ impl Promise {
             //    a. Let thenFinally be onFinally.
             //    b. Let catchFinally be onFinally.
             // 7. Return ? Invoke(promise, "then", « thenFinally, catchFinally »).
-            let then = promise.get(utf16!("then"), context)?;
+            let then = promise.get(js_str!("then"), context)?;
             return then.call(this, &[on_finally.clone(), on_finally.clone()], context);
         };
 
@@ -1675,7 +1675,7 @@ impl Promise {
             Self::then_catch_finally_closures(c, on_finally, context);
 
         // 7. Return ? Invoke(promise, "then", « thenFinally, catchFinally »).
-        let then = promise.get(utf16!("then"), context)?;
+        let then = promise.get(js_str!("then"), context)?;
         then.call(this, &[then_finally.into(), catch_finally.into()], context)
     }
 
@@ -1730,7 +1730,7 @@ impl Promise {
                     let value_thunk = return_value.length(0).name("").build();
 
                     // v. Return ? Invoke(promise, "then", « valueThunk »).
-                    promise.invoke(utf16!("then"), &[value_thunk.into()], context)
+                    promise.invoke(js_str!("then"), &[value_thunk.into()], context)
                 },
                 FinallyCaptures {
                     on_finally: on_finally.clone(),
@@ -1781,7 +1781,7 @@ impl Promise {
                     let thrower = throw_reason.length(0).name("").build();
 
                     // v. Return ? Invoke(promise, "then", « thrower »).
-                    promise.invoke(utf16!("then"), &[thrower.into()], context)
+                    promise.invoke(js_str!("then"), &[thrower.into()], context)
                 },
                 FinallyCaptures { on_finally, c },
             ),
@@ -1986,7 +1986,7 @@ impl Promise {
         context: &mut Context,
     ) -> JsResult<JsObject> {
         // 1. Let promiseResolve be ? Get(promiseConstructor, "resolve").
-        let promise_resolve = promise_constructor.get(utf16!("resolve"), context)?;
+        let promise_resolve = promise_constructor.get(js_str!("resolve"), context)?;
 
         // 2. If IsCallable(promiseResolve) is false, throw a TypeError exception.
         promise_resolve.as_callable().cloned().ok_or_else(|| {
@@ -2184,7 +2184,7 @@ impl Promise {
                     };
 
                     // 9. Let then be Completion(Get(resolution, "then")).
-                    let then_action = match then.get(utf16!("then"), context) {
+                    let then_action = match then.get(js_str!("then"), context) {
                         // 10. If then is an abrupt completion, then
                         Err(e) => {
                             //   a. Perform RejectPromise(promise, then.[[Value]]).

core/engine/src/builtins/proxy/mod.rs

@@ -26,11 +26,12 @@ use crate::{
     },
     property::{PropertyDescriptor, PropertyKey},
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     value::Type,
     Context, JsArgs, JsResult, JsString, JsValue,
 };
 use boa_gc::{Finalize, GcRefCell, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use rustc_hash::FxHashSet;
 
@@ -233,12 +234,12 @@ impl Proxy {
 
         // 6. Perform ! CreateDataPropertyOrThrow(result, "proxy", p).
         result
-            .create_data_property_or_throw(utf16!("proxy"), p, context)
+            .create_data_property_or_throw(js_str!("proxy"), p, context)
             .expect("CreateDataPropertyOrThrow cannot fail here");
 
         // 7. Perform ! CreateDataPropertyOrThrow(result, "revoke", revoker).
         result
-            .create_data_property_or_throw(utf16!("revoke"), revoker, context)
+            .create_data_property_or_throw(js_str!("revoke"), revoker, context)
             .expect("CreateDataPropertyOrThrow cannot fail here");
 
         // 8. Return result.
@@ -266,7 +267,7 @@ pub(crate) fn proxy_exotic_get_prototype_of(
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "getPrototypeOf").
-    let Some(trap) = handler.get_method(utf16!("getPrototypeOf"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("getPrototypeOf"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? target.[[GetPrototypeOf]]().
         return target.__get_prototype_of__(context);
@@ -327,7 +328,7 @@ pub(crate) fn proxy_exotic_set_prototype_of(
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "setPrototypeOf").
-    let Some(trap) = handler.get_method(utf16!("setPrototypeOf"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("setPrototypeOf"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? target.[[SetPrototypeOf]](V).
         return target.__set_prototype_of__(val, context);
@@ -386,7 +387,7 @@ pub(crate) fn proxy_exotic_is_extensible(obj: &JsObject, context: &mut Context)
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "isExtensible").
-    let Some(trap) = handler.get_method(utf16!("isExtensible"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("isExtensible"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? IsExtensible(target).
         return target.is_extensible(context);
@@ -431,7 +432,7 @@ pub(crate) fn proxy_exotic_prevent_extensions(
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "preventExtensions").
-    let Some(trap) = handler.get_method(utf16!("preventExtensions"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("preventExtensions"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? target.[[PreventExtensions]]().
         return target.__prevent_extensions__(context);
@@ -478,7 +479,7 @@ pub(crate) fn proxy_exotic_get_own_property(
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "getOwnPropertyDescriptor").
-    let Some(trap) = handler.get_method(utf16!("getOwnPropertyDescriptor"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("getOwnPropertyDescriptor"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? target.[[GetOwnProperty]](P).
         return target.__get_own_property__(key, context);
@@ -603,7 +604,7 @@ pub(crate) fn proxy_exotic_define_own_property(
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "defineProperty").
-    let Some(trap) = handler.get_method(utf16!("defineProperty"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("defineProperty"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? target.[[DefineOwnProperty]](P, Desc).
         return target.__define_own_property__(key, desc, context);
@@ -715,7 +716,7 @@ pub(crate) fn proxy_exotic_has_property(
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "has").
-    let Some(trap) = handler.get_method(utf16!("has"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("has"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? target.[[HasProperty]](P).
         return target.has_property(key.clone(), context);
@@ -783,7 +784,7 @@ pub(crate) fn proxy_exotic_get(
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "get").
-    let Some(trap) = handler.get_method(utf16!("get"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("get"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? target.[[Get]](P, Receiver).
         return target.__get__(key, receiver, context);
@@ -853,7 +854,7 @@ pub(crate) fn proxy_exotic_set(
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "set").
-    let Some(trap) = handler.get_method(utf16!("set"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("set"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? target.[[Set]](P, V, Receiver).
         return target.__set__(key, value, receiver, context);
@@ -933,7 +934,7 @@ pub(crate) fn proxy_exotic_delete(
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "deleteProperty").
-    let Some(trap) = handler.get_method(utf16!("deleteProperty"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("deleteProperty"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? target.[[Delete]](P).
         return target.__delete__(key, context);
@@ -998,7 +999,7 @@ pub(crate) fn proxy_exotic_own_property_keys(
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "ownKeys").
-    let Some(trap) = handler.get_method(utf16!("ownKeys"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("ownKeys"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? target.[[OwnPropertyKeys]]().
         return target.__own_property_keys__(context);
@@ -1132,7 +1133,7 @@ fn proxy_exotic_call(
         .try_data()?;
 
     // 5. Let trap be ? GetMethod(handler, "apply").
-    let Some(trap) = handler.get_method(utf16!("apply"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("apply"), context)? else {
         // 6. If trap is undefined, then
         // a. Return ? Call(target, thisArgument, argumentsList).
         return Ok(target.__call__(argument_count));
@@ -1180,7 +1181,7 @@ fn proxy_exotic_construct(
     assert!(target.is_constructor());
 
     // 6. Let trap be ? GetMethod(handler, "construct").
-    let Some(trap) = handler.get_method(utf16!("construct"), context)? else {
+    let Some(trap) = handler.get_method(js_str!("construct"), context)? else {
         // 7. If trap is undefined, then
         // a. Return ? Construct(target, argumentsList, newTarget).
         return Ok(target.__construct__(argument_count));

core/engine/src/builtins/reflect/tests.rs

@@ -1,4 +1,5 @@
-use crate::{js_string, run_test_actions, JsValue, TestAction};
+use crate::{run_test_actions, JsValue, TestAction};
+use boa_macros::js_str;
 use indoc::indoc;
 
 #[test]
@@ -68,10 +69,7 @@ fn get_prototype_of() {
                 function F() { this.p = 42 };
                 let f = new F();
             "#}),
-        TestAction::assert_eq(
-            "Reflect.getPrototypeOf(f).constructor.name",
-            js_string!("F"),
-        ),
+        TestAction::assert_eq("Reflect.getPrototypeOf(f).constructor.name", js_str!("F")),
     ]);
 }
 
@@ -134,6 +132,6 @@ fn set_prototype_of() {
                 let obj = {}
                 Reflect.setPrototypeOf(obj, F);
             "#}),
-        TestAction::assert_eq("Reflect.getPrototypeOf(obj).name", js_string!("F")),
+        TestAction::assert_eq("Reflect.getPrototypeOf(obj).name", js_str!("F")),
     ]);
 }

core/engine/src/builtins/regexp/mod.rs

@@ -17,12 +17,13 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject, CONSTRUCTOR},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16, CodePoint},
+    string::{common::StaticJsStrings, CodePoint, JsStrVariant},
     symbol::JsSymbol,
     value::JsValue,
     Context, JsArgs, JsData, JsResult, JsString,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::{js_str, utf16};
 use boa_parser::lexer::regex::RegExpFlags;
 use boa_profiler::Profiler;
 use regress::{Flags, Range, Regex};
@@ -238,12 +239,12 @@ impl BuiltInConstructor for RegExp {
             (p, f)
         } else if let Some(pattern) = pattern_is_regexp {
             // a. Let P be ? Get(pattern, "source").
-            let p = pattern.get(js_string!("source"), context)?;
+            let p = pattern.get(js_str!("source"), context)?;
 
             // b. If flags is undefined, then
             let f = if flags.is_undefined() {
                 // i. Let F be ? Get(pattern, "flags").
-                pattern.get(js_string!("flags"), context)?
+                pattern.get(js_str!("flags"), context)?
             // c. Else,
             } else {
                 // i. Let F be flags.
@@ -636,54 +637,54 @@ impl RegExp {
         };
 
         // 3. Let codeUnits be a new empty List.
-        let mut code_units = Vec::new();
+        let mut code_units = String::new();
 
         // 4. Let hasIndices be ToBoolean(? Get(R, "hasIndices")).
         // 5. If hasIndices is true, append the code unit 0x0064 (LATIN SMALL LETTER D) to codeUnits.
-        if object.get(utf16!("hasIndices"), context)?.to_boolean() {
-            code_units.extend_from_slice(utf16!("d"));
+        if object.get(js_str!("hasIndices"), context)?.to_boolean() {
+            code_units.push('d');
         }
 
         // 6. Let global be ToBoolean(? Get(R, "global")).
         // 7. If global is true, append the code unit 0x0067 (LATIN SMALL LETTER G) to codeUnits.
-        if object.get(utf16!("global"), context)?.to_boolean() {
-            code_units.extend_from_slice(utf16!("g"));
+        if object.get(js_str!("global"), context)?.to_boolean() {
+            code_units.push('g');
         }
 
         // 8. Let ignoreCase be ToBoolean(? Get(R, "ignoreCase")).
         // 9. If ignoreCase is true, append the code unit 0x0069 (LATIN SMALL LETTER I) to codeUnits.
-        if object.get(utf16!("ignoreCase"), context)?.to_boolean() {
-            code_units.extend_from_slice(utf16!("i"));
+        if object.get(js_str!("ignoreCase"), context)?.to_boolean() {
+            code_units.push('i');
         }
 
         // 10. Let multiline be ToBoolean(? Get(R, "multiline")).
         // 11. If multiline is true, append the code unit 0x006D (LATIN SMALL LETTER M) to codeUnits.
-        if object.get(utf16!("multiline"), context)?.to_boolean() {
-            code_units.extend_from_slice(utf16!("m"));
+        if object.get(js_str!("multiline"), context)?.to_boolean() {
+            code_units.push('m');
         }
 
         // 12. Let dotAll be ToBoolean(? Get(R, "dotAll")).
         // 13. If dotAll is true, append the code unit 0x0073 (LATIN SMALL LETTER S) to codeUnits.
-        if object.get(utf16!("dotAll"), context)?.to_boolean() {
-            code_units.extend_from_slice(utf16!("s"));
+        if object.get(js_str!("dotAll"), context)?.to_boolean() {
+            code_units.push('s');
         }
 
         // 14. Let unicode be ToBoolean(? Get(R, "unicode")).
         // 15. If unicode is true, append the code unit 0x0075 (LATIN SMALL LETTER U) to codeUnits.
-        if object.get(utf16!("unicode"), context)?.to_boolean() {
-            code_units.extend_from_slice(utf16!("u"));
+        if object.get(js_str!("unicode"), context)?.to_boolean() {
+            code_units.push('u');
         }
 
         // 16. Let unicodeSets be ToBoolean(? Get(R, "unicodeSets")).
         // 17. If unicodeSets is true, append the code unit 0x0076 (LATIN SMALL LETTER V) to codeUnits.
-        if object.get(utf16!("unicodeSets"), context)?.to_boolean() {
-            code_units.extend_from_slice(utf16!("v"));
+        if object.get(js_str!("unicodeSets"), context)?.to_boolean() {
+            code_units.push('v');
         }
 
         // 18. Let sticky be ToBoolean(? Get(R, "sticky")).
         // 19. If sticky is true, append the code unit 0x0079 (LATIN SMALL LETTER Y) to codeUnits.
-        if object.get(utf16!("sticky"), context)?.to_boolean() {
-            code_units.extend_from_slice(utf16!("y"));
+        if object.get(js_str!("sticky"), context)?.to_boolean() {
+            code_units.push('y');
         }
 
         // 20. Return the String value whose code units are the elements of the List codeUnits.
@@ -724,7 +725,7 @@ impl RegExp {
                     this,
                     &JsValue::new(context.intrinsics().constructors().regexp().prototype()),
                 ) {
-                    Ok(JsValue::new(js_string!("(?:)")))
+                    Ok(JsValue::new(js_str!("(?:)")))
                 } else {
                     Err(JsNativeError::typ()
                         .with_message("RegExp.prototype.source method called on incompatible value")
@@ -752,7 +753,7 @@ impl RegExp {
     /// [spec]: https://tc39.es/ecma262/#sec-escaperegexppattern
     fn escape_pattern(src: &JsString, _flags: &JsString) -> JsValue {
         if src.is_empty() {
-            js_string!("(?:)").into()
+            js_str!("(?:)").into()
         } else {
             let mut s = Vec::with_capacity(src.len());
             let mut buf = [0; 2];
@@ -863,7 +864,7 @@ impl RegExp {
         // 2. Assert: Type(S) is String.
 
         // 3. Let exec be ? Get(R, "exec").
-        let exec = this.get(utf16!("exec"), context)?;
+        let exec = this.get(js_str!("exec"), context)?;
 
         // 4. If IsCallable(exec) is true, then
         if let Some(exec) = exec.as_callable() {
@@ -915,19 +916,21 @@ impl RegExp {
         let length = input.len() as u64;
 
         // 2. Let lastIndex be ℝ(? ToLength(? Get(R, "lastIndex"))).
-        let mut last_index = this.get(utf16!("lastIndex"), context)?.to_length(context)?;
+        let mut last_index = this
+            .get(js_str!("lastIndex"), context)?
+            .to_length(context)?;
 
         // 3. Let flags be R.[[OriginalFlags]].
         let flags = &rx.original_flags;
 
         // 4. If flags contains "g", let global be true; else let global be false.
-        let global = flags.contains(&('g' as u16));
+        let global = flags.contains(b'g');
 
         // 5. If flags contains "y", let sticky be true; else let sticky be false.
-        let sticky = flags.contains(&('y' as u16));
+        let sticky = flags.contains(b'y');
 
         // 6. If flags contains "d", let hasIndices be true; else let hasIndices be false.
-        let has_indices = flags.contains(&('d' as u16));
+        let has_indices = flags.contains(b'd');
 
         // 7. If global is false and sticky is false, set lastIndex to 0.
         if !global && !sticky {
@@ -938,7 +941,7 @@ impl RegExp {
         let matcher = &rx.matcher;
 
         // 9. If flags contains "u" or flags contains "v", let fullUnicode be true; else let fullUnicode be false.
-        let full_unicode = flags.contains(&('u' as u16)) || flags.contains(&('v' as u16));
+        let full_unicode = flags.contains(b'u') || flags.contains(b'v');
 
         // NOTE: The following steps are take care of by regress:
         //
@@ -952,7 +955,7 @@ impl RegExp {
             // i. If global is true or sticky is true, then
             if global || sticky {
                 // 1. Perform ? Set(R, "lastIndex", +0𝔽, true).
-                this.set(utf16!("lastIndex"), 0, true, context)?;
+                this.set(js_str!("lastIndex"), 0, true, context)?;
             }
 
             // ii. Return null.
@@ -961,10 +964,20 @@ impl RegExp {
 
         // 13.b. Let inputIndex be the index into input of the character that was obtained from element lastIndex of S.
         // 13.c. Let r be matcher(input, inputIndex).
-        let r: Option<regress::Match> = if full_unicode {
-            matcher.find_from_utf16(input, last_index as usize).next()
-        } else {
-            matcher.find_from_ucs2(input, last_index as usize).next()
+        let r: Option<regress::Match> = match (full_unicode, input.as_str().variant()) {
+            (true | false, JsStrVariant::Latin1(_)) => {
+                // TODO: Currently regress does not support latin1 encoding.
+                let input = input.to_vec();
+
+                // NOTE: We can use the faster ucs2 variant since there will never be two byte unicode.
+                matcher.find_from_ucs2(&input, last_index as usize).next()
+            }
+            (true, JsStrVariant::Utf16(input)) => {
+                matcher.find_from_utf16(input, last_index as usize).next()
+            }
+            (false, JsStrVariant::Utf16(input)) => {
+                matcher.find_from_ucs2(input, last_index as usize).next()
+            }
         };
 
         let Some(match_value) = r else {
@@ -975,7 +988,7 @@ impl RegExp {
             //       13.a.i. If global is true or sticky is true, then
             if global || sticky {
                 // 1. Perform ? Set(R, "lastIndex", +0𝔽, true).
-                this.set(utf16!("lastIndex"), 0, true, context)?;
+                this.set(js_str!("lastIndex"), 0, true, context)?;
             }
 
             // MOVE: ii. Set lastIndex to AdvanceStringIndex(S, lastIndex, fullUnicode).
@@ -994,7 +1007,7 @@ impl RegExp {
         // NOTE: regress currently doesn't support the sticky flag so we have to emulate it.
         if sticky && match_value.start() != last_index as usize {
             // 1. Perform ? Set(R, "lastIndex", +0𝔽, true).
-            this.set(utf16!("lastIndex"), 0, true, context)?;
+            this.set(js_str!("lastIndex"), 0, true, context)?;
 
             // 2. Return null.
             return Ok(None);
@@ -1012,7 +1025,7 @@ impl RegExp {
         // 16. If global is true or sticky is true, then
         if global || sticky {
             // a. Perform ? Set(R, "lastIndex", 𝔽(e), true).
-            this.set(utf16!("lastIndex"), e, true, context)?;
+            this.set(js_str!("lastIndex"), e, true, context)?;
         }
 
         // 17. Let n be the number of elements in r's captures List.
@@ -1026,11 +1039,11 @@ impl RegExp {
         let a = Array::array_create(n + 1, None, context)?;
 
         // 22. Perform ! CreateDataPropertyOrThrow(A, "index", 𝔽(lastIndex)).
-        a.create_data_property_or_throw(utf16!("index"), last_index, context)
+        a.create_data_property_or_throw(js_str!("index"), last_index, context)
             .expect("this CreateDataPropertyOrThrow call must not fail");
 
         // 23. Perform ! CreateDataPropertyOrThrow(A, "input", S).
-        a.create_data_property_or_throw(utf16!("input"), input.clone(), context)
+        a.create_data_property_or_throw(js_str!("input"), input.clone(), context)
             .expect("this CreateDataPropertyOrThrow call must not fail");
 
         // 24. Let match be the Match Record { [[StartIndex]]: lastIndex, [[EndIndex]]: e }.
@@ -1051,7 +1064,7 @@ impl RegExp {
             .expect("this CreateDataPropertyOrThrow call must not fail");
 
         // 28. Let matchedSubstr be GetMatchString(S, match).
-        let matched_substr = js_string!(&input[(last_index as usize)..(e)]);
+        let matched_substr = input.get_expect((last_index as usize)..(e));
 
         // 29. Perform ! CreateDataPropertyOrThrow(A, "0", matchedSubstr).
         a.create_data_property_or_throw(0, matched_substr, context)
@@ -1081,7 +1094,7 @@ impl RegExp {
             for (name, range) in named_groups {
                 let name = js_string!(name);
                 if let Some(range) = range {
-                    let value = js_string!(&input[range.clone()]);
+                    let value = input.get_expect(range.clone());
 
                     groups
                         .create_data_property_or_throw(name.clone(), value, context)
@@ -1126,11 +1139,11 @@ impl RegExp {
         // 22.2.7.8 MakeMatchIndicesIndexPairArray ( S, indices, groupNames, hasGroups )
         // 8. Perform ! CreateDataPropertyOrThrow(A, "groups", groups).
         indices
-            .create_data_property_or_throw(utf16!("groups"), group_names, context)
+            .create_data_property_or_throw(js_str!("groups"), group_names, context)
             .expect("this CreateDataPropertyOrThrow call must not fail");
 
         // 32. Perform ! CreateDataPropertyOrThrow(A, "groups", groups).
-        a.create_data_property_or_throw(utf16!("groups"), groups, context)
+        a.create_data_property_or_throw(js_str!("groups"), groups, context)
             .expect("this CreateDataPropertyOrThrow call must not fail");
 
         // 27. For each integer i such that i ≥ 1 and i ≤ n, in ascending order, do
@@ -1141,9 +1154,9 @@ impl RegExp {
             // b. If captureI is undefined, let capturedValue be undefined.
             // c. Else if fullUnicode is true, then
             // d. Else,
-            let captured_value = capture
-                .clone()
-                .map_or_else(JsValue::undefined, |range| js_string!(&input[range]).into());
+            let captured_value = capture.clone().map_or_else(JsValue::undefined, |range| {
+                js_string!(input.get_expect(range)).into()
+            });
 
             // e. Perform ! CreateDataPropertyOrThrow(A, ! ToString(𝔽(i)), capturedValue).
             a.create_data_property_or_throw(i, captured_value.clone(), context)
@@ -1171,7 +1184,7 @@ impl RegExp {
         // a. Let indicesArray be MakeMatchIndicesIndexPairArray(S, indices, groupNames, hasGroups).
         // b. Perform ! CreateDataPropertyOrThrow(A, "indices", indicesArray).
         if has_indices {
-            a.create_data_property_or_throw(utf16!("indices"), indices, context)
+            a.create_data_property_or_throw(js_str!("indices"), indices, context)
                 .expect("this CreateDataPropertyOrThrow call must not fail");
         }
 
@@ -1206,10 +1219,10 @@ impl RegExp {
         let arg_str = args.get_or_undefined(0).to_string(context)?;
 
         // 4. Let flags be ? ToString(? Get(rx, "flags")).
-        let flags = rx.get(utf16!("flags"), context)?.to_string(context)?;
+        let flags = rx.get(js_str!("flags"), context)?.to_string(context)?;
 
         // 5. If flags does not contain "g", then
-        if !flags.contains(&103) {
+        if !flags.contains(b'g') {
             // a. Return ? RegExpExec(rx, S).
             return (Self::abstract_exec(rx, arg_str, context)?)
                 .map_or_else(|| Ok(JsValue::null()), |v| Ok(v.into()));
@@ -1218,10 +1231,10 @@ impl RegExp {
         // 6. Else,
 
         // a. If flags contains "u" or flags contains "v", let fullUnicode be true. Otherwise, let fullUnicode be false.
-        let full_unicode = flags.contains(&117) || flags.contains(&118);
+        let full_unicode = flags.contains(b'u') || flags.contains(b'v');
 
         // b. Perform ? Set(rx, "lastIndex", +0𝔽, true).
-        rx.set(utf16!("lastIndex"), 0, true, context)?;
+        rx.set(js_str!("lastIndex"), 0, true, context)?;
 
         // c. Let A be ! ArrayCreate(0).
         let a = Array::array_create(0, None, context).expect("this ArrayCreate call must not fail");
@@ -1247,13 +1260,18 @@ impl RegExp {
                 // 3. If matchStr is the empty String, then
                 if match_str.is_empty() {
                     // a. Let thisIndex be ℝ(? ToLength(? Get(rx, "lastIndex"))).
-                    let this_index = rx.get(utf16!("lastIndex"), context)?.to_length(context)?;
+                    let this_index = rx.get(js_str!("lastIndex"), context)?.to_length(context)?;
 
                     // b. Let nextIndex be AdvanceStringIndex(S, thisIndex, fullUnicode).
                     let next_index = advance_string_index(&arg_str, this_index, full_unicode);
 
                     // c. Perform ? Set(rx, "lastIndex", 𝔽(nextIndex), true).
-                    rx.set(utf16!("lastIndex"), JsValue::new(next_index), true, context)?;
+                    rx.set(
+                        js_str!("lastIndex"),
+                        JsValue::new(next_index),
+                        true,
+                        context,
+                    )?;
                 }
 
                 // 4. Set n to n + 1.
@@ -1293,14 +1311,14 @@ impl RegExp {
         })?;
 
         // 3. Let pattern be ? ToString(? Get(R, "source")).
-        let pattern = regexp.get(utf16!("source"), context)?.to_string(context)?;
+        let pattern = regexp.get(js_str!("source"), context)?.to_string(context)?;
 
         // 4. Let flags be ? ToString(? Get(R, "flags")).
-        let flags = regexp.get(utf16!("flags"), context)?.to_string(context)?;
+        let flags = regexp.get(js_str!("flags"), context)?.to_string(context)?;
 
         // 5. Let result be the string-concatenation of "/", pattern, "/", and flags.
         // 6. Return result.
-        Ok(js_string!(utf16!("/"), &pattern, utf16!("/"), &flags).into())
+        Ok(js_string!(js_str!("/"), &pattern, js_str!("/"), &flags).into())
     }
 
     /// `RegExp.prototype[ @@matchAll ]( string )`
@@ -1332,26 +1350,26 @@ impl RegExp {
         let c = regexp.species_constructor(StandardConstructors::regexp, context)?;
 
         // 5. Let flags be ? ToString(? Get(R, "flags")).
-        let flags = regexp.get(utf16!("flags"), context)?.to_string(context)?;
+        let flags = regexp.get(js_str!("flags"), context)?.to_string(context)?;
 
         // 6. Let matcher be ? Construct(C, « R, flags »).
         let matcher = c.construct(&[this.clone(), flags.clone().into()], Some(&c), context)?;
 
         // 7. Let lastIndex be ? ToLength(? Get(R, "lastIndex")).
         let last_index = regexp
-            .get(utf16!("lastIndex"), context)?
+            .get(js_str!("lastIndex"), context)?
             .to_length(context)?;
 
         // 8. Perform ? Set(matcher, "lastIndex", lastIndex, true).
-        matcher.set(utf16!("lastIndex"), last_index, true, context)?;
+        matcher.set(js_str!("lastIndex"), last_index, true, context)?;
 
         // 9. If flags contains "g", let global be true.
         // 10. Else, let global be false.
-        let global = flags.contains(&('g' as u16));
+        let global = flags.contains(b'g');
 
         // 11. If flags contains "u", let fullUnicode be true.
         // 12. Else, let fullUnicode be false.
-        let unicode = flags.contains(&('u' as u16));
+        let unicode = flags.contains(b'u');
 
         // 13. Return ! CreateRegExpStringIterator(matcher, S, global, fullUnicode).
         Ok(RegExpStringIterator::create_regexp_string_iterator(
@@ -1414,18 +1432,18 @@ impl RegExp {
         };
 
         // 7. Let flags be ? ToString(? Get(rx, "flags")).
-        let flags = rx.get(utf16!("flags"), context)?.to_string(context)?;
+        let flags = rx.get(js_str!("flags"), context)?.to_string(context)?;
 
         // 8. If flags contains "g", let global be true. Otherwise, let global be false.
-        let global = flags.as_slice().contains(&u16::from(b'g'));
+        let global = flags.contains(b'g');
 
         // 9. If global is true, then
         let full_unicode = if global {
             // a. If flags contains "u", let fullUnicode be true. Otherwise, let fullUnicode be false.
-            let full_unicode = flags.contains(&u16::from(b'u'));
+            let full_unicode = flags.contains(b'u');
 
             // b. Perform ? Set(rx, "lastIndex", +0𝔽, true).
-            rx.set(utf16!("lastIndex"), 0, true, context)?;
+            rx.set(js_str!("lastIndex"), 0, true, context)?;
 
             full_unicode
         } else {
@@ -1467,13 +1485,18 @@ impl RegExp {
             //    2. If matchStr is the empty String, then
             if match_str.is_empty() {
                 // a. Let thisIndex be ℝ(? ToLength(? Get(rx, "lastIndex"))).
-                let this_index = rx.get(utf16!("lastIndex"), context)?.to_length(context)?;
+                let this_index = rx.get(js_str!("lastIndex"), context)?.to_length(context)?;
 
                 // b. Let nextIndex be AdvanceStringIndex(S, thisIndex, fullUnicode).
                 let next_index = advance_string_index(&s, this_index, full_unicode);
 
                 // c. Perform ? Set(rx, "lastIndex", 𝔽(nextIndex), true).
-                rx.set(utf16!("lastIndex"), JsValue::new(next_index), true, context)?;
+                rx.set(
+                    js_str!("lastIndex"),
+                    JsValue::new(next_index),
+                    true,
+                    context,
+                )?;
             }
         }
 
@@ -1502,7 +1525,7 @@ impl RegExp {
 
             // e. Let position be ? ToIntegerOrInfinity(? Get(result, "index")).
             let position = result
-                .get(utf16!("index"), context)?
+                .get(js_str!("index"), context)?
                 .to_integer_or_infinity(context)?;
 
             // f. Set position to the result of clamping position between 0 and lengthS.
@@ -1534,7 +1557,7 @@ impl RegExp {
             }
 
             // j. Let namedCaptures be ? Get(result, "groups").
-            let mut named_captures = result.get(utf16!("groups"), context)?;
+            let mut named_captures = result.get(js_str!("groups"), context)?;
 
             let replacement = match replace_value {
                 // k. If functionalReplace is true, then
@@ -1587,8 +1610,8 @@ impl RegExp {
                 //    In such cases, the corresponding substitution is ignored.
 
                 // ii. Set accumulatedResult to the string-concatenation of accumulatedResult, the substring of S from nextSourcePosition to position, and replacement.
-                accumulated_result.extend_from_slice(&s[next_source_position..position]);
-                accumulated_result.extend_from_slice(&replacement);
+                accumulated_result.extend(s.get_expect(next_source_position..position).iter());
+                accumulated_result.extend(replacement.iter());
 
                 // iii. Set nextSourcePosition to position + matchLength.
                 next_source_position = position + match_length;
@@ -1597,11 +1620,15 @@ impl RegExp {
 
         // 16. If nextSourcePosition ≥ lengthS, return accumulatedResult.
         if next_source_position >= length_s {
-            return Ok(js_string!(accumulated_result).into());
+            return Ok(js_string!(&accumulated_result[..]).into());
         }
 
         // 17. Return the string-concatenation of accumulatedResult and the substring of S from nextSourcePosition.
-        Ok(js_string!(&accumulated_result[..], &s[next_source_position..]).into())
+        Ok(js_string!(
+            &JsString::from(&accumulated_result[..]),
+            s.get_expect(next_source_position..)
+        )
+        .into())
     }
 
     /// `RegExp.prototype[ @@search ]( string )`
@@ -1630,31 +1657,31 @@ impl RegExp {
         let arg_str = args.get_or_undefined(0).to_string(context)?;
 
         // 4. Let previousLastIndex be ? Get(rx, "lastIndex").
-        let previous_last_index = rx.get(utf16!("lastIndex"), context)?;
+        let previous_last_index = rx.get(js_str!("lastIndex"), context)?;
 
         // 5. If SameValue(previousLastIndex, +0𝔽) is false, then
         if !JsValue::same_value(&previous_last_index, &JsValue::new(0)) {
             // a. Perform ? Set(rx, "lastIndex", +0𝔽, true).
-            rx.set(utf16!("lastIndex"), 0, true, context)?;
+            rx.set(js_str!("lastIndex"), 0, true, context)?;
         }
 
         // 6. Let result be ? RegExpExec(rx, S).
         let result = Self::abstract_exec(rx, arg_str, context)?;
 
         // 7. Let currentLastIndex be ? Get(rx, "lastIndex").
-        let current_last_index = rx.get(utf16!("lastIndex"), context)?;
+        let current_last_index = rx.get(js_str!("lastIndex"), context)?;
 
         // 8. If SameValue(currentLastIndex, previousLastIndex) is false, then
         if !JsValue::same_value(&current_last_index, &previous_last_index) {
             // a. Perform ? Set(rx, "lastIndex", previousLastIndex, true).
-            rx.set(utf16!("lastIndex"), previous_last_index, true, context)?;
+            rx.set(js_str!("lastIndex"), previous_last_index, true, context)?;
         }
 
         // 9. If result is null, return -1𝔽.
         // 10. Return ? Get(result, "index").
         result.map_or_else(
             || Ok(JsValue::new(-1)),
-            |result| result.get(utf16!("index"), context),
+            |result| result.get(js_str!("index"), context),
         )
     }
 
@@ -1687,18 +1714,18 @@ impl RegExp {
         let constructor = rx.species_constructor(StandardConstructors::regexp, context)?;
 
         // 5. Let flags be ? ToString(? Get(rx, "flags")).
-        let flags = rx.get(utf16!("flags"), context)?.to_string(context)?;
+        let flags = rx.get(js_str!("flags"), context)?.to_string(context)?;
 
         // 6. If flags contains "u", let unicodeMatching be true.
         // 7. Else, let unicodeMatching be false.
-        let unicode = flags.contains(&('u' as u16));
+        let unicode = flags.contains(b'u');
 
         // 8. If flags contains "y", let newFlags be flags.
         // 9. Else, let newFlags be the string-concatenation of flags and "y".
-        let new_flags = if flags.contains(&('y' as u16)) {
+        let new_flags = if flags.contains(b'y') {
             flags
         } else {
-            js_string!(&flags, utf16!("y"))
+            js_string!(&flags, js_str!("y"))
         };
 
         // 10. Let splitter be ? Construct(C, « rx, newFlags »).
@@ -1756,7 +1783,7 @@ impl RegExp {
         // 19. Repeat, while q < size,
         while q < size {
             // a. Perform ? Set(splitter, "lastIndex", 𝔽(q), true).
-            splitter.set(utf16!("lastIndex"), JsValue::new(q), true, context)?;
+            splitter.set(js_str!("lastIndex"), JsValue::new(q), true, context)?;
 
             // b. Let z be ? RegExpExec(splitter, S).
             let result = Self::abstract_exec(&splitter, arg_str.clone(), context)?;
@@ -1766,7 +1793,7 @@ impl RegExp {
             if let Some(result) = result {
                 // i. Let e be ℝ(? ToLength(? Get(splitter, "lastIndex"))).
                 let mut e = splitter
-                    .get(utf16!("lastIndex"), context)?
+                    .get(js_str!("lastIndex"), context)?
                     .to_length(context)?;
 
                 // ii. Set e to min(e, size).
@@ -1778,7 +1805,7 @@ impl RegExp {
                     q = advance_string_index(&arg_str, q, unicode);
                 } else {
                     // 1. Let T be the substring of S from p to q.
-                    let arg_str_substring = js_string!(&arg_str[p as usize..q as usize]);
+                    let arg_str_substring = arg_str.get_expect(p as usize..q as usize);
 
                     // 2. Perform ! CreateDataPropertyOrThrow(A, ! ToString(𝔽(lengthA)), T).
                     a.create_data_property_or_throw(length_a, arg_str_substring, context)
@@ -1829,7 +1856,7 @@ impl RegExp {
         }
 
         // 20. Let T be the substring of S from p to size.
-        let arg_str_substring = js_string!(&arg_str[p as usize..size as usize]);
+        let arg_str_substring = arg_str.get_expect(p as usize..size as usize);
 
         // 21. Perform ! CreateDataPropertyOrThrow(A, ! ToString(𝔽(lengthA)), T).
         a.create_data_property_or_throw(length_a, arg_str_substring, context)
@@ -1890,7 +1917,7 @@ impl RegExp {
                 .expect("already checked that the object was a RegExp") = regexp;
         }
 
-        this.set(utf16!("lastIndex"), 0, true, context)?;
+        this.set(js_str!("lastIndex"), 0, true, context)?;
 
         Ok(this.into())
     }

core/engine/src/builtins/regexp/regexp_string_iterator.rs

@@ -18,11 +18,11 @@ use crate::{
     object::JsObject,
     property::Attribute,
     realm::Realm,
-    string::utf16,
     symbol::JsSymbol,
     Context, JsData, JsResult, JsString, JsValue,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use regexp::{advance_string_index, RegExp};
 
@@ -160,7 +160,7 @@ impl RegExpStringIterator {
                 // 1. Let thisIndex be ℝ(? ToLength(? Get(R, "lastIndex"))).
                 let this_index = iterator
                     .matcher
-                    .get(utf16!("lastIndex"), context)?
+                    .get(js_str!("lastIndex"), context)?
                     .to_length(context)?;
 
                 // 2. Let nextIndex be ! AdvanceStringIndex(S, thisIndex, fullUnicode).
@@ -170,7 +170,7 @@ impl RegExpStringIterator {
                 // 3. Perform ? Set(R, "lastIndex", 𝔽(nextIndex), true).
                 iterator
                     .matcher
-                    .set(utf16!("lastIndex"), next_index, true, context)?;
+                    .set(js_str!("lastIndex"), next_index, true, context)?;
             }
 
             // vi. Perform ? Yield(match).

core/engine/src/builtins/regexp/tests.rs

@@ -2,6 +2,7 @@ use crate::{
     js_string, native_function::NativeFunctionObject, run_test_actions, JsNativeErrorKind,
     JsObject, JsValue, TestAction,
 };
+use boa_macros::js_str;
 use indoc::indoc;
 
 #[test]
@@ -36,7 +37,7 @@ fn species() {
         // return-value
         TestAction::assert("Object.is(accessor.call(thisVal), thisVal)"),
         // symbol-species-name
-        TestAction::assert_eq("name.value", js_string!("get [Symbol.species]")),
+        TestAction::assert_eq("name.value", js_str!("get [Symbol.species]")),
         TestAction::assert("!name.enumerable"),
         TestAction::assert("!name.writable"),
         TestAction::assert("name.configurable"),
@@ -65,7 +66,7 @@ fn flags() {
         TestAction::assert("!re_gi.dotAll"),
         TestAction::assert("!re_gi.unicode"),
         TestAction::assert("!re_gi.sticky"),
-        TestAction::assert_eq("re_gi.flags", js_string!("gi")),
+        TestAction::assert_eq("re_gi.flags", js_str!("gi")),
         //
         TestAction::assert("!re_sm.global"),
         TestAction::assert("!re_sm.ignoreCase"),
@@ -73,7 +74,7 @@ fn flags() {
         TestAction::assert("re_sm.dotAll"),
         TestAction::assert("!re_sm.unicode"),
         TestAction::assert("!re_sm.sticky"),
-        TestAction::assert_eq("re_sm.flags", js_string!("ms")),
+        TestAction::assert_eq("re_sm.flags", js_str!("ms")),
         //
         TestAction::assert("!re_u.global"),
         TestAction::assert("!re_u.ignoreCase"),
@@ -81,7 +82,7 @@ fn flags() {
         TestAction::assert("!re_u.dotAll"),
         TestAction::assert("re_u.unicode"),
         TestAction::assert("!re_u.sticky"),
-        TestAction::assert_eq("re_u.flags", js_string!("u")),
+        TestAction::assert_eq("re_u.flags", js_str!("u")),
     ]);
 }
 
@@ -114,7 +115,7 @@ fn exec() {
         TestAction::assert_eq("result.index", 4),
         TestAction::assert_eq(
             "result.input",
-            js_string!("The Quick Brown Fox Jumps Over The Lazy Dog"),
+            js_str!("The Quick Brown Fox Jumps Over The Lazy Dog"),
         ),
     ]);
 }
@@ -138,8 +139,8 @@ fn no_panic_on_parse_fail() {
 #[test]
 fn to_string() {
     run_test_actions([
-        TestAction::assert_eq("(new RegExp('a+b+c')).toString()", js_string!("/a+b+c/")),
-        TestAction::assert_eq("(new RegExp('bar', 'g')).toString()", js_string!("/bar/g")),
+        TestAction::assert_eq("(new RegExp('a+b+c')).toString()", js_str!("/a+b+c/")),
+        TestAction::assert_eq("(new RegExp('bar', 'g')).toString()", js_str!("/bar/g")),
         TestAction::assert_eq(r"(new RegExp('\\n', 'g')).toString()", js_string!(r"/\n/g")),
         TestAction::assert_eq(r"/\n/g.toString()", js_string!(r"/\n/g")),
         TestAction::assert_eq(r"/,\;/.toString()", js_string!(r"/,\;/")),
@@ -164,7 +165,7 @@ fn search() {
         TestAction::assert("!length.writable"),
         TestAction::assert("length.configurable"),
         // name
-        TestAction::assert_eq("name.value", js_string!("[Symbol.search]")),
+        TestAction::assert_eq("name.value", js_str!("[Symbol.search]")),
         TestAction::assert("!name.enumerable"),
         TestAction::assert("!name.writable"),
         TestAction::assert("name.configurable"),

core/engine/src/builtins/set/mod.rs

@@ -26,10 +26,11 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::{Attribute, PropertyNameKind},
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     symbol::JsSymbol,
     Context, JsArgs, JsResult, JsString, JsValue,
 };
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use num_traits::Zero;
 
@@ -71,18 +72,18 @@ impl IntrinsicObject for Set {
             .method(Self::for_each, js_string!("forEach"), 1)
             .method(Self::has, js_string!("has"), 1)
             .property(
-                utf16!("keys"),
+                js_string!("keys"),
                 values_function.clone(),
                 Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("size"),
+                js_string!("size"),
                 Some(size_getter),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .property(
-                utf16!("values"),
+                js_string!("values"),
                 values_function.clone(),
                 Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
             )
@@ -138,7 +139,7 @@ impl BuiltInConstructor for Set {
         }
 
         // 5. Let adder be ? Get(set, "add").
-        let adder = set.get(utf16!("add"), context)?;
+        let adder = set.get(js_str!("add"), context)?;
 
         // 6. If IsCallable(adder) is false, throw a TypeError exception.
         let adder = adder.as_callable().ok_or_else(|| {

core/engine/src/builtins/string/mod.rs

@@ -17,12 +17,12 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, JsObject},
     property::{Attribute, PropertyDescriptor},
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
-    string::{CodePoint, Utf16Trim},
+    string::{common::StaticJsStrings, CodePoint},
     symbol::JsSymbol,
     value::IntegerOrInfinity,
     Context, JsArgs, JsResult, JsString, JsValue,
 };
+use boa_macros::{js_str, utf16};
 use boa_profiler::Profiler;
 use icu_normalizer::{ComposingNormalizer, DecomposingNormalizer};
 use std::cmp::{max, min};
@@ -32,6 +32,9 @@ use super::{BuiltInBuilder, BuiltInConstructor, IntrinsicObject};
 mod string_iterator;
 pub(crate) use string_iterator::StringIterator;
 
+#[cfg(feature = "annex-b")]
+pub use crate::JsStr;
+
 /// The set of normalizers required for the `String.prototype.normalize` function.
 #[derive(Debug)]
 pub(crate) struct StringNormalizers {
@@ -70,6 +73,23 @@ pub(crate) const fn is_trimmable_whitespace(c: char) -> bool {
     )
 }
 
+/// Helper function to check if a `u8` latin1 character is trimmable.
+pub(crate) const fn is_trimmable_whitespace_latin1(c: u8) -> bool {
+    // The rust implementation of `trim` does not regard the same characters whitespace as ecma standard does
+    //
+    // Rust uses \p{White_Space} by default, which also includes:
+    // `\u{0085}' (next line)
+    // And does not include:
+    // '\u{FEFF}' (zero width non-breaking space)
+    // Explicit whitespace: https://tc39.es/ecma262/#sec-white-space
+    matches!(
+        c,
+        0x09 | 0x0B | 0x0C | 0x20 | 0xA0 |
+        // Line terminators: https://tc39.es/ecma262/#sec-line-terminators
+        0x0A | 0x0D
+    )
+}
+
 /// JavaScript `String` implementation.
 #[derive(Debug, Clone, Copy)]
 pub(crate) struct String;
@@ -382,7 +402,7 @@ impl String {
         let cooked = args.get_or_undefined(0).to_object(context)?;
 
         // 3. Let raw be ? ToObject(? Get(cooked, "raw")).
-        let raw = cooked.get(utf16!("raw"), context)?.to_object(context)?;
+        let raw = cooked.get(js_str!("raw"), context)?.to_object(context)?;
 
         // 4. Let literalSegments be ? LengthOfArrayLike(raw).
         let literal_segments = raw.length_of_array_like(context)?;
@@ -407,13 +427,13 @@ impl String {
             let next_seg = raw.get(next_key, context)?.to_string(context)?;
 
             // c. Append the code unit elements of nextSeg to the end of stringElements.
-            string_elements.extend(next_seg.iter().copied());
+            string_elements.extend(next_seg.iter());
 
             // d. If nextIndex + 1 = literalSegments, then
             if next_index + 1 == literal_segments {
                 // i. Return the String value whose code units are the elements in the List stringElements.
                 //    If stringElements has no elements, the empty String is returned.
-                return Ok(js_string!(string_elements).into());
+                return Ok(js_string!(&string_elements[..]).into());
             }
 
             // e. If nextIndex < numberOfSubstitutions, let next be substitutions[nextIndex].
@@ -429,7 +449,7 @@ impl String {
             let next_sub = next.to_string(context)?;
 
             // h. Append the code unit elements of nextSub to the end of stringElements.
-            string_elements.extend(next_sub.iter().copied());
+            string_elements.extend(next_sub.iter());
 
             // i. Set nextIndex to nextIndex + 1.
             next_index += 1;
@@ -461,7 +481,7 @@ impl String {
         }
 
         // 3. Return result.
-        Ok(js_string!(result).into())
+        Ok(js_string!(&result[..]).into())
     }
 
     /// `String.prototype.toString ( )`
@@ -511,7 +531,7 @@ impl String {
             // 6. Return the substring of S from position to position + 1.
             IntegerOrInfinity::Integer(i) if i >= 0 && i < string.len() as i64 => {
                 let i = i as usize;
-                Ok(js_string!(&string[i..=i]).into())
+                Ok(js_string!(string.get_expect(i..=i)).into())
             }
             // 5. If position < 0 or position ≥ size, return the empty String.
             _ => Ok(js_string!().into()),
@@ -553,7 +573,7 @@ impl String {
         };
 
         // 8. Return the substring of S from k to k + 1.
-        Ok(js_string!(&s[k..=k]).into())
+        Ok(js_string!(s.get_expect(k..=k)).into())
     }
 
     /// `String.prototype.codePointAt( index )`
@@ -629,9 +649,11 @@ impl String {
 
         match position {
             // 4. Let size be the length of S.
-            IntegerOrInfinity::Integer(i) if i >= 0 && i < string.len() as i64 => {
+            IntegerOrInfinity::Integer(i) if i >= 0 => {
                 // 6. Return the Number value for the numeric value of the code unit at index position within the String S.
-                Ok(u32::from(string[i as usize]).into())
+                Ok(string
+                    .get(i as usize)
+                    .map_or_else(JsValue::nan, JsValue::from))
             }
             // 5. If position < 0 or position ≥ size, return NaN.
             _ => Ok(JsValue::nan()),
@@ -708,14 +730,14 @@ impl String {
                     return Ok(js_string!().into());
                 }
                 let n = n as usize;
-                let mut result = Vec::with_capacity(n * len);
+                let mut result = Vec::with_capacity(n);
 
-                std::iter::repeat(&string[..])
+                std::iter::repeat(string.as_str())
                     .take(n)
-                    .for_each(|s| result.extend_from_slice(s));
+                    .for_each(|s| result.push(s));
 
                 // 6. Return the String value that is made from n copies of S appended together.
-                Ok(js_string!(result).into())
+                Ok(JsString::concat_array(&result).into())
             }
             // 5. If n is 0, return the empty String.
             IntegerOrInfinity::Integer(0) => Ok(js_string!().into()),
@@ -790,7 +812,7 @@ impl String {
             Ok(js_string!().into())
         } else {
             // 13. Return the substring of S from from to to.
-            Ok(js_string!(&string[from..to]).into())
+            Ok(js_string!(string.get_expect(from..to)).into())
         }
     }
 
@@ -859,7 +881,7 @@ impl String {
             // 14. Return ! SameValueNonNumeric(substring, searchStr).
             // `SameValueNonNumeric` forwards to `==`, so directly check
             // equality to avoid converting to `JsValue`
-            Ok(JsValue::new(search_string == string[start..end]))
+            Ok(JsValue::new(search_string == string.get_expect(start..end)))
         }
     }
 
@@ -922,7 +944,7 @@ impl String {
             // 14. Return ! SameValueNonNumeric(substring, searchStr).
             // `SameValueNonNumeric` forwards to `==`, so directly check
             // equality to avoid converting to `JsValue`
-            Ok(JsValue::new(search_str == string[start..end]))
+            Ok(JsValue::new(search_str == string.get_expect(start..end)))
         } else {
             // 12. If start < 0, return false.
             Ok(false.into())
@@ -973,7 +995,7 @@ impl String {
         // 10. Let index be ! StringIndexOf(S, searchStr, start).
         // 11. If index is not -1, return true.
         // 12. Return false.
-        Ok(string.index_of(&search_str, start).is_some().into())
+        Ok(string.index_of(search_str.as_str(), start).is_some().into())
     }
 
     /// `String.prototype.replace( regexp|substr, newSubstr|function )`
@@ -1042,12 +1064,12 @@ impl String {
 
         // 8. Let position be ! StringIndexOf(string, searchString, 0).
         // 9. If position is -1, return string.
-        let Some(position) = string.index_of(&search_string, 0) else {
+        let Some(position) = string.index_of(search_string.as_str(), 0) else {
             return Ok(string.into());
         };
 
         // 10. Let preserved be the substring of string from 0 to position.
-        let preserved = &string[..position];
+        let preserved = JsString::from(string.get_expect(..position));
 
         let replacement = match replace_value {
             // 11. If functionalReplace is true, then
@@ -1081,7 +1103,12 @@ impl String {
         };
 
         // 13. Return the string-concatenation of preserved, replacement, and the substring of string from position + searchLength.
-        Ok(js_string!(preserved, &replacement, &string[position + search_length..]).into())
+        Ok(js_string!(
+            &preserved,
+            &replacement,
+            &JsString::from(string.get_expect(position + search_length..))
+        )
+        .into())
     }
 
     /// `22.1.3.18 String.prototype.replaceAll ( searchValue, replaceValue )`
@@ -1117,13 +1144,13 @@ impl String {
             // b. If isRegExp is true, then
             if let Some(obj) = RegExp::is_reg_exp(search_value, context)? {
                 // i. Let flags be ? Get(searchValue, "flags").
-                let flags = obj.get(utf16!("flags"), context)?;
+                let flags = obj.get(js_str!("flags"), context)?;
 
                 // ii. Perform ? RequireObjectCoercible(flags).
                 flags.require_object_coercible()?;
 
                 // iii. If ? ToString(flags) does not contain "g", throw a TypeError exception.
-                if !flags.to_string(context)?.contains(&u16::from(b'g')) {
+                if !flags.to_string(context)?.contains(b'g') {
                     return Err(JsNativeError::typ()
                         .with_message(
                             "String.prototype.replaceAll called with a non-global RegExp argument",
@@ -1167,7 +1194,7 @@ impl String {
         let mut match_positions = Vec::new();
 
         // 10. Let position be ! StringIndexOf(string, searchString, 0).
-        let mut position = string.index_of(&search_string, 0);
+        let mut position = string.index_of(search_string.as_str(), 0);
 
         // 11. Repeat, while position is not -1,
         while let Some(p) = position {
@@ -1175,7 +1202,7 @@ impl String {
             match_positions.push(p);
 
             // b. Set position to ! StringIndexOf(string, searchString, position + advanceBy).
-            position = string.index_of(&search_string, p + advance_by);
+            position = string.index_of(search_string.as_str(), p + advance_by);
         }
 
         // 12. Let endOfLastMatch be 0.
@@ -1187,7 +1214,7 @@ impl String {
         // 14. For each element p of matchPositions, do
         for p in match_positions {
             // a. Let preserved be the substring of string from endOfLastMatch to p.
-            let preserved = &string[end_of_last_match..p];
+            let preserved = string.get_expect(end_of_last_match..p);
 
             // c. Else,
             let replacement = match replace {
@@ -1222,8 +1249,8 @@ impl String {
             };
 
             // d. Set result to the string-concatenation of result, preserved, and replacement.
-            result.extend_from_slice(preserved);
-            result.extend_from_slice(&replacement);
+            result.extend(preserved.iter());
+            result.extend(replacement.iter());
 
             // e. Set endOfLastMatch to p + searchLength.
             end_of_last_match = p + search_length;
@@ -1232,11 +1259,11 @@ impl String {
         // 15. If endOfLastMatch < the length of string, then
         if end_of_last_match < string.len() {
             // a. Set result to the string-concatenation of result and the substring of string from endOfLastMatch.
-            result.extend_from_slice(&string[end_of_last_match..]);
+            result.extend(string.get_expect(end_of_last_match..).iter());
         }
 
         // 16. Return result.
-        Ok(js_string!(result).into())
+        Ok(js_string!(&result[..]).into())
     }
 
     /// `String.prototype.indexOf( searchValue[, fromIndex] )`
@@ -1278,7 +1305,7 @@ impl String {
 
         // 8. Return 𝔽(! StringIndexOf(S, searchStr, start)).
         Ok(string
-            .index_of(&search_str, start)
+            .index_of(search_str.as_str(), start)
             .map_or(-1, |i| i as i64)
             .into())
     }
@@ -1368,10 +1395,10 @@ impl String {
             // 11. For each non-negative integer i starting with start such that i ≤ len - searchLen, in descending order, do
             for i in (0..=min(start, end)).rev() {
                 // a. Let candidate be the substring of S from i to i + searchLen.
-                let candidate = &string[i..i + search_len];
+                let candidate = string.get_expect(i..i + search_len);
 
                 // b. If candidate is the same sequence of code units as searchStr, return 𝔽(i).
-                if candidate == &search_str {
+                if candidate == search_str {
                     return Ok(i.into());
                 }
             }
@@ -1431,6 +1458,9 @@ impl String {
                     .expect("constructor must return a `Collator` object")
                     .collator();
 
+                let s = s.iter().collect::<Vec<_>>();
+                let that_value = that_value.iter().collect::<Vec<_>>();
+
                 collator.compare_utf16(&s, &that_value) as i8
             }
 
@@ -1544,15 +1574,15 @@ impl String {
             }
         };
 
-        let truncated_string_filler = filler.repeat(repetitions as usize);
-        let truncated_string_filler = &truncated_string_filler[..fill_len as usize];
+        let truncated_string_filler = filler.to_vec().repeat(repetitions as usize);
+        let truncated_string_filler = JsString::from(&truncated_string_filler[..fill_len as usize]);
 
         // 10. If placement is start, return the string-concatenation of truncatedStringFiller and S.
         if placement == Placement::Start {
-            Ok(js_string!(truncated_string_filler, &string).into())
+            Ok(js_string!(&truncated_string_filler, &string).into())
         } else {
             // 11. Else, return the string-concatenation of S and truncatedStringFiller.
-            Ok(js_string!(&string, truncated_string_filler).into())
+            Ok(js_string!(&string, &truncated_string_filler).into())
         }
     }
 
@@ -1876,7 +1906,7 @@ impl String {
         let to = max(final_start, final_end);
 
         // 10. Return the substring of S from from to to.
-        Ok(js_string!(&string[from..to]).into())
+        Ok(js_string!(string.get_expect(from..to)).into())
     }
 
     /// `String.prototype.split ( separator, limit )`
@@ -1946,9 +1976,10 @@ impl String {
             // b. Let codeUnits be a List consisting of the sequence of code units that are the elements of head.
             let head = this_str
                 .get(..lim)
-                .unwrap_or(&this_str[..])
+                .unwrap_or(this_str.as_str())
                 .iter()
-                .map(|code| js_string!(std::slice::from_ref(code)).into());
+                .map(|code| js_string!(std::slice::from_ref(&code)).into());
+
             // c. Return ! CreateArrayFromList(codeUnits).
             return Ok(Array::create_array_from_list(head, context).into());
         }
@@ -1965,13 +1996,13 @@ impl String {
         let mut i = 0;
 
         // 13. Let j be ! StringIndexOf(S, R, 0).
-        let mut j = this_str.index_of(&separator_str, 0);
+        let mut j = this_str.index_of(separator_str.as_str(), 0);
 
         // 14. Repeat, while j is not -1
         while let Some(index) = j {
             // a. Let T be the substring of S from i to j.
             // b. Append T as the last element of substrings.
-            substrings.push(js_string!(&this_str[i..index]));
+            substrings.push(this_str.get_expect(i..index).into());
 
             // c. If the number of elements of substrings is lim, return ! CreateArrayFromList(substrings).
             if substrings.len() == lim {
@@ -1985,12 +2016,12 @@ impl String {
             i = index + separator_length;
 
             // e. Set j to ! StringIndexOf(S, R, i).
-            j = this_str.index_of(&separator_str, i);
+            j = this_str.index_of(separator_str.as_str(), i);
         }
 
         // 15. Let T be the substring of S from i.
         // 16. Append T to substrings.
-        substrings.push(js_string!(&this_str[i..]));
+        substrings.push(JsString::from(this_str.get_expect(i..)));
 
         // 17. Return ! CreateArrayFromList(substrings).
         Ok(
@@ -2045,13 +2076,13 @@ impl String {
             // b. If isRegExp is true, then
             if let Some(regexp) = RegExp::is_reg_exp(regexp, context)? {
                 // i. Let flags be ? Get(regexp, "flags").
-                let flags = regexp.get(utf16!("flags"), context)?;
+                let flags = regexp.get(js_str!("flags"), context)?;
 
                 // ii. Perform ? RequireObjectCoercible(flags).
                 flags.require_object_coercible()?;
 
                 // iii. If ? ToString(flags) does not contain "g", throw a TypeError exception.
-                if !flags.to_string(context)?.contains(&u16::from(b'g')) {
+                if !flags.to_string(context)?.contains(b'g') {
                     return Err(JsNativeError::typ()
                         .with_message(
                             "String.prototype.matchAll called with a non-global RegExp argument",
@@ -2071,7 +2102,7 @@ impl String {
         let s = o.to_string(context)?;
 
         // 4. Let rx be ? RegExpCreate(regexp, "g").
-        let rx = RegExp::create(regexp, &JsValue::new(js_string!("g")), context)?;
+        let rx = RegExp::create(regexp, &JsValue::new(js_str!("g")), context)?;
 
         // 5. Return ? Invoke(rx, @@matchAll, « S »).
         rx.invoke(JsSymbol::match_all(), &[JsValue::new(s)], context)
@@ -2115,10 +2146,10 @@ impl String {
             &JsValue::Undefined => Normalization::Nfc,
             // 4. Else, let f be ? ToString(form).
             f => match f.to_string(context)? {
-                ntype if &ntype == utf16!("NFC") => Normalization::Nfc,
-                ntype if &ntype == utf16!("NFD") => Normalization::Nfd,
-                ntype if &ntype == utf16!("NFKC") => Normalization::Nfkc,
-                ntype if &ntype == utf16!("NFKD") => Normalization::Nfkd,
+                ntype if &ntype == "NFC" => Normalization::Nfc,
+                ntype if &ntype == "NFD" => Normalization::Nfd,
+                ntype if &ntype == "NFKC" => Normalization::Nfkc,
+                ntype if &ntype == "NFKD" => Normalization::Nfkd,
                 // 5. If f is not one of "NFC", "NFD", "NFKC", or "NFKD", throw a RangeError exception.
                 _ => {
                     return Err(JsNativeError::range()
@@ -2147,6 +2178,8 @@ impl String {
             }
         };
 
+        let s = s.iter().collect::<Vec<_>>();
+
         let result = match normalization {
             Normalization::Nfc => normalizers.nfc.normalize_utf16(&s),
             Normalization::Nfd => normalizers.nfd.normalize_utf16(&s),
@@ -2155,7 +2188,7 @@ impl String {
         };
 
         // 7. Return ns.
-        Ok(js_string!(result).into())
+        Ok(js_string!(&result[..]).into())
     }
 
     /// `String.prototype.search( regexp )`
@@ -2276,7 +2309,7 @@ impl String {
 
         // 11. Return the substring of S from intStart to intEnd.
         if let Some(substr) = s.get(int_start..int_end) {
-            Ok(js_string!(substr).into())
+            Ok(substr.into())
         } else {
             Ok(js_string!().into())
         }
@@ -2290,8 +2323,8 @@ impl String {
     /// [spec]: https://tc39.es/ecma262/#sec-createhtml
     pub(crate) fn create_html(
         string: &JsValue,
-        tag: &[u16],
-        attribute_and_value: Option<(&[u16], &JsValue)>,
+        tag: JsStr<'_>,
+        attribute_and_value: Option<(JsStr<'_>, &JsValue)>,
         context: &mut Context,
     ) -> JsResult<JsValue> {
         // 1. Let str be ? RequireObjectCoercible(string).
@@ -2301,7 +2334,7 @@ impl String {
         let s = str.to_string(context)?;
 
         // 3. Let p1 be the string-concatenation of "<" and tag.
-        let mut p1 = JsString::concat_array(&[utf16!("<"), tag]);
+        let mut p1 = js_string!(js_str!("<"), tag);
 
         // 4. If attribute is not the empty String, then
         if let Some((attribute, value)) = attribute_and_value {
@@ -2312,7 +2345,7 @@ impl String {
             //    of the code unit 0x0022 (QUOTATION MARK) in V has been replaced with the six
             //    code unit sequence "&quot;".
             let mut escaped_v = Vec::with_capacity(v.len());
-            for c in v.as_slice().iter().copied() {
+            for c in &v {
                 if c == 0x0022 {
                     escaped_v.extend(utf16!("&quot;"));
                     continue;
@@ -2328,27 +2361,20 @@ impl String {
             //    the code unit 0x0022 (QUOTATION MARK)
             //    escapedV
             //    the code unit 0x0022 (QUOTATION MARK)
-            p1 = JsString::concat_array(&[
-                p1.as_slice(),
-                utf16!(" "),
+            p1 = js_string!(
+                &p1,
+                js_str!(" "),
                 attribute,
-                utf16!("=\""),
-                escaped_v.as_slice(),
-                utf16!("\""),
-            ]);
+                js_str!("=\""),
+                &JsString::from(&escaped_v[..]),
+                js_str!("\"")
+            );
         }
 
         // 5. Let p2 be the string-concatenation of p1 and ">".
         // 6. Let p3 be the string-concatenation of p2 and S.
         // 7. Let p4 be the string-concatenation of p3, "</", tag, and ">".
-        let p4 = JsString::concat_array(&[
-            p1.as_slice(),
-            utf16!(">"),
-            s.as_slice(),
-            utf16!("</"),
-            tag,
-            utf16!(">"),
-        ]);
+        let p4 = js_string!(&p1, js_str!(">"), &s, js_str!("</"), tag, js_str!(">"));
 
         // 8. Return p4.
         Ok(p4.into())
@@ -2372,7 +2398,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "a", "name", name).
-        Self::create_html(s, utf16!("a"), Some((utf16!("name"), name)), context)
+        Self::create_html(s, js_str!("a"), Some((js_str!("name"), name)), context)
     }
 
     /// `String.prototype.big( )`
@@ -2387,7 +2413,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "big", "", "").
-        Self::create_html(s, utf16!("big"), None, context)
+        Self::create_html(s, js_str!("big"), None, context)
     }
 
     /// `String.prototype.blink( )`
@@ -2402,7 +2428,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "blink", "", "").
-        Self::create_html(s, utf16!("blink"), None, context)
+        Self::create_html(s, js_str!("blink"), None, context)
     }
 
     /// `String.prototype.bold( )`
@@ -2417,7 +2443,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "b", "", "").
-        Self::create_html(s, utf16!("b"), None, context)
+        Self::create_html(s, js_str!("b"), None, context)
     }
 
     /// `String.prototype.fixed( )`
@@ -2432,7 +2458,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "big", "", "").
-        Self::create_html(s, utf16!("tt"), None, context)
+        Self::create_html(s, js_str!("tt"), None, context)
     }
 
     /// `String.prototype.fontcolor( color )`
@@ -2453,7 +2479,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "font", "color", color).
-        Self::create_html(s, utf16!("font"), Some((utf16!("color"), color)), context)
+        Self::create_html(s, js_str!("font"), Some((js_str!("color"), color)), context)
     }
 
     /// `String.prototype.fontsize( size )`
@@ -2474,7 +2500,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "font", "size", size).
-        Self::create_html(s, utf16!("font"), Some((utf16!("size"), size)), context)
+        Self::create_html(s, js_str!("font"), Some((js_str!("size"), size)), context)
     }
 
     /// `String.prototype.italics( )`
@@ -2493,7 +2519,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "i", "", "").
-        Self::create_html(s, utf16!("i"), None, context)
+        Self::create_html(s, js_str!("i"), None, context)
     }
 
     /// `String.prototype.link( url )`
@@ -2514,7 +2540,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "a", "href", url).
-        Self::create_html(s, utf16!("a"), Some((utf16!("href"), url)), context)
+        Self::create_html(s, js_str!("a"), Some((js_str!("href"), url)), context)
     }
 
     /// `String.prototype.small( )`
@@ -2529,7 +2555,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "small", "", "").
-        Self::create_html(s, utf16!("small"), None, context)
+        Self::create_html(s, js_str!("small"), None, context)
     }
 
     /// `String.prototype.strike( )`
@@ -2548,7 +2574,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "strike", "", "").
-        Self::create_html(s, utf16!("strike"), None, context)
+        Self::create_html(s, js_str!("strike"), None, context)
     }
 
     /// `String.prototype.sub( )`
@@ -2563,7 +2589,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "sub", "", "").
-        Self::create_html(s, utf16!("sub"), None, context)
+        Self::create_html(s, js_str!("sub"), None, context)
     }
 
     /// `String.prototype.sup( )`
@@ -2578,7 +2604,7 @@ impl String {
         // 1. Let S be the this value.
         let s = this;
         // 2. Return ? CreateHTML(S, "sup", "", "").
-        Self::create_html(s, utf16!("sup"), None, context)
+        Self::create_html(s, js_str!("sup"), None, context)
     }
 }
 
@@ -2639,19 +2665,19 @@ pub(crate) fn get_substitution(
                 // $&
                 Some(CodePoint::Unicode('&')) => {
                     // matched
-                    result.extend_from_slice(matched);
+                    result.extend(matched.iter());
                 }
                 // $`
                 Some(CodePoint::Unicode('`')) => {
                     // The replacement is the substring of str from 0 to position.
-                    result.extend_from_slice(&str[..position]);
+                    result.extend(str.get_expect(..position).iter());
                 }
                 // $'
                 Some(CodePoint::Unicode('\'')) => {
                     // If tailPos ≥ stringLength, the replacement is the empty String.
                     // Otherwise the replacement is the substring of str from tailPos.
                     if tail_pos < str_length {
-                        result.extend_from_slice(&str[tail_pos..]);
+                        result.extend(str.get_expect(tail_pos..).iter());
                     }
                 }
                 // $nn
@@ -2698,7 +2724,7 @@ pub(crate) fn get_substitution(
                         //     a. Let refReplacement be capture.
                         if let Some(capture) = captures.get(index - 1) {
                             if let Some(s) = capture.as_string() {
-                                result.extend_from_slice(s);
+                                result.extend(s.iter());
                             }
                         }
 
@@ -2742,14 +2768,14 @@ pub(crate) fn get_substitution(
                         // d. Else,
                         } else {
                             // i. Let groupName be the enclosed substring.
-                            let group_name = js_string!(group_name);
+                            let group_name = js_string!(&group_name[..]);
                             // ii. Let capture be ? Get(namedCaptures, groupName).
                             let capture = named_captures.get(group_name, context)?;
 
                             // iii. If capture is undefined, replace the text through > with the empty String.
                             // iv. Otherwise, replace the text through > with ? ToString(capture).
                             if !capture.is_undefined() {
-                                result.extend_from_slice(&capture.to_string(context)?);
+                                result.extend(capture.to_string(context)?.iter());
                             }
                         }
                     }
@@ -2768,5 +2794,5 @@ pub(crate) fn get_substitution(
     }
 
     // 11. Return result.
-    Ok(js_string!(result))
+    Ok(js_string!(&result[..]))
 }

core/engine/src/builtins/string/tests.rs

@@ -1,3 +1,4 @@
+use boa_macros::js_str;
 use indoc::indoc;
 
 use crate::{js_string, run_test_actions, JsNativeErrorKind, JsValue, TestAction};
@@ -56,11 +57,11 @@ fn concat() {
             "#}),
         TestAction::assert_eq(
             "hello.concat(world, nice)",
-            js_string!("Hello, world! Have a nice day."),
+            js_str!("Hello, world! Have a nice day."),
         ),
         TestAction::assert_eq(
             "hello + world + nice",
-            js_string!("Hello, world! Have a nice day."),
+            js_str!("Hello, world! Have a nice day."),
         ),
     ]);
 }
@@ -72,10 +73,7 @@ fn generic_concat() {
                 Number.prototype.concat = String.prototype.concat;
                 let number = new Number(100);
             "#}),
-        TestAction::assert_eq(
-            "number.concat(' - 50', ' = 50')",
-            js_string!("100 - 50 = 50"),
-        ),
+        TestAction::assert_eq("number.concat(' - 50', ' = 50')", js_str!("100 - 50 = 50")),
     ]);
 }
 
@@ -100,8 +98,8 @@ fn repeat() {
         TestAction::assert_eq("empty.repeat(1)", js_string!()),
         TestAction::assert_eq("en.repeat(0)", js_string!()),
         TestAction::assert_eq("zh.repeat(0)", js_string!()),
-        TestAction::assert_eq("en.repeat(1)", js_string!("english")),
-        TestAction::assert_eq("zh.repeat(2)", js_string!("中文中文")),
+        TestAction::assert_eq("en.repeat(1)", js_str!("english")),
+        TestAction::assert_eq("zh.repeat(2)", js_str!("中文中文")),
     ]);
 }
 
@@ -140,9 +138,9 @@ fn repeat_generic() {
     run_test_actions([
         TestAction::run("Number.prototype.repeat = String.prototype.repeat;"),
         TestAction::assert_eq("(0).repeat(0)", js_string!()),
-        TestAction::assert_eq("(1).repeat(1)", js_string!("1")),
-        TestAction::assert_eq("(1).repeat(5)", js_string!("11111")),
-        TestAction::assert_eq("(12).repeat(3)", js_string!("121212")),
+        TestAction::assert_eq("(1).repeat(1)", js_str!("1")),
+        TestAction::assert_eq("(1).repeat(5)", js_str!("11111")),
+        TestAction::assert_eq("(12).repeat(3)", js_str!("121212")),
     ]);
 }
 
@@ -152,7 +150,7 @@ fn replace() {
         indoc! {r#"
             "abc".replace("a", "2")
         "#},
-        js_string!("2bc"),
+        js_str!("2bc"),
     )]);
 }
 
@@ -162,7 +160,7 @@ fn replace_no_match() {
         indoc! {r#"
             "abc".replace(/d/, "$&$&")
         "#},
-        js_string!("abc"),
+        js_str!("abc"),
     )]);
 }
 
@@ -172,7 +170,7 @@ fn replace_with_capture_groups() {
         indoc! {r#"
             "John Smith".replace(/(\w+)\s(\w+)/, '$2, $1')
         "#},
-        js_string!("Smith, John"),
+        js_str!("Smith, John"),
     )]);
 }
 
@@ -183,7 +181,7 @@ fn replace_with_tenth_capture_group() {
             var re = /(\d)(\d)(\d)(\d)(\d)(\d)(\d)(\d)(\d)(\d)/;
             "0123456789".replace(re, '$10')
         "#},
-        js_string!("9"),
+        js_str!("9"),
     )]);
 }
 
@@ -199,11 +197,11 @@ fn replace_substitutions() {
             var end = a.replace(re, " $' ");
             var no_sub = a.replace(re, " $_ ");
         "#}),
-        TestAction::assert_eq("a.replace(re, \" $$ \")", js_string!("one $ three")),
-        TestAction::assert_eq("a.replace(re, \"$&$&\")", js_string!("one two  two three")),
-        TestAction::assert_eq("a.replace(re, \" $` \")", js_string!("one one three")),
-        TestAction::assert_eq("a.replace(re, \" $' \")", js_string!("one three three")),
-        TestAction::assert_eq("a.replace(re, \" $_ \")", js_string!("one $_ three")),
+        TestAction::assert_eq("a.replace(re, \" $$ \")", js_str!("one $ three")),
+        TestAction::assert_eq("a.replace(re, \"$&$&\")", js_str!("one two  two three")),
+        TestAction::assert_eq("a.replace(re, \" $` \")", js_str!("one one three")),
+        TestAction::assert_eq("a.replace(re, \" $' \")", js_str!("one three three")),
+        TestAction::assert_eq("a.replace(re, \" $_ \")", js_str!("one $_ three")),
     ]);
 }
 
@@ -222,11 +220,11 @@ fn replace_with_function() {
             "#}),
         TestAction::assert_eq(
             "\"ecmascript is cool\".replace(/c(o)(o)(l)/, replacer)",
-            js_string!("ecmascript is awesome!"),
+            js_str!("ecmascript is awesome!"),
         ),
-        TestAction::assert_eq("p1", js_string!("o")),
-        TestAction::assert_eq("p2", js_string!("o")),
-        TestAction::assert_eq("p3", js_string!("l")),
+        TestAction::assert_eq("p1", js_str!("o")),
+        TestAction::assert_eq("p2", js_str!("o")),
+        TestAction::assert_eq("p3", js_str!("l")),
         TestAction::assert_eq("length", 14),
     ]);
 }
@@ -329,7 +327,7 @@ fn match_all_one() {
             )
         "#}),
         TestAction::assert_eq("m1.value.index", 0),
-        TestAction::assert_eq("m1.value.input", js_string!("test1test2")),
+        TestAction::assert_eq("m1.value.input", js_str!("test1test2")),
         TestAction::assert_eq("m1.value.groups", JsValue::undefined()),
         TestAction::assert(indoc! {r#"
             arrayEquals(
@@ -338,7 +336,7 @@ fn match_all_one() {
             )
         "#}),
         TestAction::assert_eq("m2.value.index", 5),
-        TestAction::assert_eq("m2.value.input", js_string!("test1test2")),
+        TestAction::assert_eq("m2.value.input", js_str!("test1test2")),
         TestAction::assert_eq("m2.value.groups", JsValue::undefined()),
         TestAction::assert_eq("m3.value", JsValue::undefined()),
     ]);
@@ -366,7 +364,7 @@ fn match_all_two() {
             )
         "#}),
         TestAction::assert_eq("m1.value.index", 6),
-        TestAction::assert_eq("m1.value.input", js_string!("table football, foosball")),
+        TestAction::assert_eq("m1.value.input", js_str!("table football, foosball")),
         TestAction::assert_eq("m1.value.groups", JsValue::undefined()),
         TestAction::assert(indoc! {r#"
             arrayEquals(
@@ -375,7 +373,7 @@ fn match_all_two() {
             )
         "#}),
         TestAction::assert_eq("m2.value.index", 16),
-        TestAction::assert_eq("m2.value.input", js_string!("table football, foosball")),
+        TestAction::assert_eq("m2.value.input", js_str!("table football, foosball")),
         TestAction::assert_eq("m2.value.groups", JsValue::undefined()),
         TestAction::assert_eq("m3.value", JsValue::undefined()),
     ]);
@@ -401,7 +399,7 @@ fn test_match() {
         TestAction::assert_eq("result1.index", 4),
         TestAction::assert_eq(
             "result1.input",
-            js_string!("The Quick Brown Fox Jumps Over The Lazy Dog"),
+            js_str!("The Quick Brown Fox Jumps Over The Lazy Dog"),
         ),
         TestAction::assert(indoc! {r#"
                 arrayEquals(
@@ -418,7 +416,7 @@ fn test_match() {
         TestAction::assert_eq("result3.index", 0),
         TestAction::assert_eq(
             "result3.input",
-            js_string!("The Quick Brown Fox Jumps Over The Lazy Dog"),
+            js_str!("The Quick Brown Fox Jumps Over The Lazy Dog"),
         ),
         TestAction::assert(indoc! {r#"
                 arrayEquals(
@@ -432,30 +430,30 @@ fn test_match() {
 #[test]
 fn trim() {
     run_test_actions([
-        TestAction::assert_eq(r"'Hello'.trim()", js_string!("Hello")),
-        TestAction::assert_eq(r"' \nHello'.trim()", js_string!("Hello")),
-        TestAction::assert_eq(r"'Hello \n\r'.trim()", js_string!("Hello")),
-        TestAction::assert_eq(r"' Hello '.trim()", js_string!("Hello")),
+        TestAction::assert_eq(r"'Hello'.trim()", js_str!("Hello")),
+        TestAction::assert_eq(r"' \nHello'.trim()", js_str!("Hello")),
+        TestAction::assert_eq(r"'Hello \n\r'.trim()", js_str!("Hello")),
+        TestAction::assert_eq(r"' Hello '.trim()", js_str!("Hello")),
     ]);
 }
 
 #[test]
 fn trim_start() {
     run_test_actions([
-        TestAction::assert_eq(r"'Hello'.trimStart()", js_string!("Hello")),
-        TestAction::assert_eq(r"' \nHello'.trimStart()", js_string!("Hello")),
-        TestAction::assert_eq(r"'Hello \n\r'.trimStart()", js_string!("Hello \n\r")),
-        TestAction::assert_eq(r"' Hello '.trimStart()", js_string!("Hello ")),
+        TestAction::assert_eq(r"'Hello'.trimStart()", js_str!("Hello")),
+        TestAction::assert_eq(r"' \nHello'.trimStart()", js_str!("Hello")),
+        TestAction::assert_eq(r"'Hello \n\r'.trimStart()", js_str!("Hello \n\r")),
+        TestAction::assert_eq(r"' Hello '.trimStart()", js_str!("Hello ")),
     ]);
 }
 
 #[test]
 fn trim_end() {
     run_test_actions([
-        TestAction::assert_eq(r"'Hello'.trimEnd()", js_string!("Hello")),
-        TestAction::assert_eq(r"' \nHello'.trimEnd()", js_string!(" \nHello")),
-        TestAction::assert_eq(r"'Hello \n\r'.trimEnd()", js_string!("Hello")),
-        TestAction::assert_eq(r"' Hello '.trimEnd()", js_string!(" Hello")),
+        TestAction::assert_eq(r"'Hello'.trimEnd()", js_str!("Hello")),
+        TestAction::assert_eq(r"' \nHello'.trimEnd()", js_str!(" \nHello")),
+        TestAction::assert_eq(r"'Hello \n\r'.trimEnd()", js_str!("Hello")),
+        TestAction::assert_eq(r"' Hello '.trimEnd()", js_str!(" Hello")),
     ]);
 }
 
@@ -578,7 +576,7 @@ fn split_with_symbol_split_method() {
                 sep_a[Symbol.split] = function(s, limit) { return s + limit.toString(); };
                 'hello'.split(sep_a, 10)
             "#},
-            js_string!("hello10"),
+            js_str!("hello10"),
         ),
         TestAction::assert(indoc! {r#"
                 let sep_b = {};
@@ -752,10 +750,10 @@ fn last_index_non_integer_position_argument() {
 fn char_at() {
     run_test_actions([
         TestAction::assert_eq("'abc'.charAt(-1)", js_string!()),
-        TestAction::assert_eq("'abc'.charAt(1)", js_string!("b")),
+        TestAction::assert_eq("'abc'.charAt(1)", js_str!("b")),
         TestAction::assert_eq("'abc'.charAt(9)", js_string!()),
-        TestAction::assert_eq("'abc'.charAt()", js_string!("a")),
-        TestAction::assert_eq("'abc'.charAt(null)", js_string!("a")),
+        TestAction::assert_eq("'abc'.charAt()", js_str!("a")),
+        TestAction::assert_eq("'abc'.charAt(null)", js_str!("a")),
         TestAction::assert_eq(r"'\uDBFF'.charAt(0)", js_string!(&[0xDBFFu16])),
     ]);
 }
@@ -794,10 +792,10 @@ fn code_point_at() {
 #[test]
 fn slice() {
     run_test_actions([
-        TestAction::assert_eq("'abc'.slice()", js_string!("abc")),
-        TestAction::assert_eq("'abc'.slice(1)", js_string!("bc")),
-        TestAction::assert_eq("'abc'.slice(-1)", js_string!("c")),
-        TestAction::assert_eq("'abc'.slice(0, 9)", js_string!("abc")),
+        TestAction::assert_eq("'abc'.slice()", js_str!("abc")),
+        TestAction::assert_eq("'abc'.slice(1)", js_str!("bc")),
+        TestAction::assert_eq("'abc'.slice(-1)", js_str!("c")),
+        TestAction::assert_eq("'abc'.slice(0, 9)", js_str!("abc")),
         TestAction::assert_eq("'abc'.slice(9, 10)", js_string!()),
     ]);
 }
@@ -844,8 +842,8 @@ fn unicode_iter() {
 fn string_get_property() {
     run_test_actions([
         TestAction::assert_eq("'abc'[-1]", JsValue::undefined()),
-        TestAction::assert_eq("'abc'[1]", js_string!("b")),
-        TestAction::assert_eq("'abc'[2]", js_string!("c")),
+        TestAction::assert_eq("'abc'[1]", js_str!("b")),
+        TestAction::assert_eq("'abc'[2]", js_str!("c")),
         TestAction::assert_eq("'abc'[3]", JsValue::undefined()),
         TestAction::assert_eq("'abc'['foo']", JsValue::undefined()),
         TestAction::assert_eq("'😀'[0]", js_string!(&[0xD83D])),
@@ -866,9 +864,9 @@ fn search() {
 fn from_code_point() {
     // Taken from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/fromCodePoint
     run_test_actions([
-        TestAction::assert_eq("String.fromCodePoint(42)", js_string!("*")),
-        TestAction::assert_eq("String.fromCodePoint(65, 90)", js_string!("AZ")),
-        TestAction::assert_eq("String.fromCodePoint(0x404)", js_string!("Є")),
+        TestAction::assert_eq("String.fromCodePoint(42)", js_str!("*")),
+        TestAction::assert_eq("String.fromCodePoint(65, 90)", js_str!("AZ")),
+        TestAction::assert_eq("String.fromCodePoint(0x404)", js_str!("Є")),
         TestAction::assert_eq(
             "String.fromCodePoint(0x2f804)",
             js_string!(&[0xD87E, 0xDC04]),
@@ -884,7 +882,7 @@ fn from_code_point() {
         ),
         TestAction::assert_eq(
             "String.fromCodePoint(9731, 9733, 9842, 0x4F60)",
-            js_string!("☃★♲你"),
+            js_str!("☃★♲你"),
         ),
         TestAction::assert_native_error(
             "String.fromCodePoint('_')",

core/engine/src/builtins/symbol/mod.rs

@@ -64,8 +64,8 @@ impl GlobalSymbolRegistry {
     }
 
     fn get_or_create_symbol(&self, key: &JsString) -> JsResult<JsSymbol> {
-        let slice = &**key;
-        if let Some(symbol) = self.keys.get(slice) {
+        let slice = key.iter().collect::<Vec<_>>();
+        if let Some(symbol) = self.keys.get(&slice[..]) {
             return Ok(symbol.clone());
         }
 
@@ -73,8 +73,10 @@ impl GlobalSymbolRegistry {
             JsNativeError::range()
                 .with_message("reached the maximum number of symbols that can be created")
         })?;
-        self.keys.insert(slice.into(), symbol.clone());
-        self.symbols.insert(symbol.clone(), slice.into());
+        self.keys
+            .insert(slice.clone().into_boxed_slice(), symbol.clone());
+        self.symbols
+            .insert(symbol.clone(), slice.into_boxed_slice());
         Ok(symbol)
     }
 

core/engine/src/builtins/symbol/tests.rs

@@ -1,4 +1,5 @@
-use crate::{js_string, run_test_actions, JsValue, TestAction};
+use crate::{run_test_actions, JsValue, TestAction};
+use boa_macros::js_str;
 use indoc::indoc;
 
 #[test]
@@ -12,7 +13,7 @@ fn call_symbol_and_check_return_type() {
 fn print_symbol_expect_description() {
     run_test_actions([TestAction::assert_eq(
         "String(Symbol('Hello'))",
-        js_string!("Symbol(Hello)"),
+        js_str!("Symbol(Hello)"),
     )]);
 }
 

core/engine/src/builtins/temporal/calendar/mod.rs

@@ -18,10 +18,11 @@ use crate::{
     object::internal_methods::get_prototype_from_constructor,
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsData, JsNativeError, JsObject, JsResult, JsString, JsSymbol, JsValue,
 };
 use boa_gc::{custom_trace, Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use temporal_rs::{
     components::calendar::{
@@ -75,7 +76,12 @@ impl IntrinsicObject for Calendar {
                 Self::NAME,
                 Attribute::CONFIGURABLE,
             )
-            .accessor(utf16!("id"), Some(get_id), None, Attribute::CONFIGURABLE)
+            .accessor(
+                js_string!("id"),
+                Some(get_id),
+                None,
+                Attribute::CONFIGURABLE,
+            )
             .static_method(Self::from, js_string!("from"), 1)
             .method(Self::date_from_fields, js_string!("dateFromFields"), 2)
             .method(
@@ -244,7 +250,7 @@ impl Calendar {
         };
 
         // 8. Let overflow be ? ToTemporalOverflow(options).
-        let overflow = get_option(&options, utf16!("overflow"), context)?
+        let overflow = get_option(&options, js_str!("overflow"), context)?
             .unwrap_or(ArithmeticOverflow::Constrain);
 
         // NOTE: implement the below on the calenar itself
@@ -327,7 +333,7 @@ impl Calendar {
         };
 
         // 7. Let overflow be ? ToTemporalOverflow(options).
-        let overflow = get_option::<ArithmeticOverflow>(&options, utf16!("overflow"), context)?
+        let overflow = get_option::<ArithmeticOverflow>(&options, js_str!("overflow"), context)?
             .unwrap_or(ArithmeticOverflow::Constrain);
 
         let result = calendar
@@ -403,7 +409,7 @@ impl Calendar {
         };
 
         // 8. Let overflow be ? ToTemporalOverflow(options).
-        let overflow = get_option(&options, utf16!("overflow"), context)?
+        let overflow = get_option(&options, js_str!("overflow"), context)?
             .unwrap_or(ArithmeticOverflow::Constrain);
 
         let result = calendar
@@ -439,7 +445,7 @@ impl Calendar {
         let options_obj = get_options_object(options)?;
 
         // 7. Let overflow be ? ToTemporalOverflow(options).
-        let overflow = get_option(&options_obj, utf16!("overflow"), context)?
+        let overflow = get_option(&options_obj, js_str!("overflow"), context)?
             .unwrap_or(ArithmeticOverflow::Constrain);
 
         // 8. Let balanceResult be ? BalanceTimeDuration(duration.[[Days]], duration.[[Hours]], duration.[[Minutes]],
@@ -476,7 +482,7 @@ impl Calendar {
         // 8. If largestUnit is "auto", set largestUnit to "day".
         let largest_unit = super::options::get_temporal_unit(
             &options,
-            utf16!("largestUnit"),
+            js_str!("largestUnit"),
             TemporalUnitGroup::Date,
             None,
             context,
@@ -1033,7 +1039,7 @@ pub(crate) fn get_temporal_calendar_slot_value_with_default(
     }
 
     // 2. Let calendarLike be ? Get(item, "calendar").
-    let calendar_like = item.get(utf16!("calendar"), context)?;
+    let calendar_like = item.get(js_str!("calendar"), context)?;
 
     // 3. Return ? ToTemporalCalendarSlotValue(calendarLike, "iso8601").
     to_temporal_calendar_slot_value(&calendar_like, context)

core/engine/src/builtins/temporal/calendar/object.rs

@@ -13,7 +13,7 @@ use crate::{
     Context, JsObject, JsString, JsValue,
 };
 
-use boa_macros::utf16;
+use boa_macros::js_str;
 use num_traits::ToPrimitive;
 use plain_date::PlainDate;
 use plain_date_time::PlainDateTime;
@@ -41,7 +41,7 @@ impl CalendarProtocol for JsObject {
         context: &mut Context,
     ) -> TemporalResult<Date<Self>> {
         let method = self
-            .get(utf16!("dateFromFields"), context)
+            .get(js_str!("dateFromFields"), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let fields = JsObject::from_temporal_fields(fields, context)
@@ -51,7 +51,7 @@ impl CalendarProtocol for JsObject {
 
         overflow_obj
             .create_data_property_or_throw(
-                utf16!("overflow"),
+                js_str!("overflow"),
                 JsString::from(overflow.to_string()),
                 context,
             )
@@ -88,7 +88,7 @@ impl CalendarProtocol for JsObject {
         context: &mut Context,
     ) -> TemporalResult<YearMonth<JsObject>> {
         let method = self
-            .get(utf16!("yearMonthFromFields"), context)
+            .get(js_str!("yearMonthFromFields"), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let fields = JsObject::from_temporal_fields(fields, context)
@@ -98,7 +98,7 @@ impl CalendarProtocol for JsObject {
 
         overflow_obj
             .create_data_property_or_throw(
-                utf16!("overflow"),
+                js_str!("overflow"),
                 JsString::from(overflow.to_string()),
                 context,
             )
@@ -137,7 +137,7 @@ impl CalendarProtocol for JsObject {
         context: &mut Context,
     ) -> TemporalResult<MonthDay<JsObject>> {
         let method = self
-            .get(utf16!("yearMonthFromFields"), context)
+            .get(js_str!("yearMonthFromFields"), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let fields = JsObject::from_temporal_fields(fields, context)
@@ -147,7 +147,7 @@ impl CalendarProtocol for JsObject {
 
         overflow_obj
             .create_data_property_or_throw(
-                utf16!("overflow"),
+                js_str!("overflow"),
                 JsString::from(overflow.to_string()),
                 context,
             )
@@ -227,7 +227,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("year")), context)
+            .get(PropertyKey::from(js_str!("year")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -269,7 +269,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("month")), context)
+            .get(PropertyKey::from(js_str!("month")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -311,7 +311,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("monthCode")), context)
+            .get(PropertyKey::from(js_str!("monthCode")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -338,7 +338,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("day")), context)
+            .get(PropertyKey::from(js_str!("day")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -380,7 +380,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("dayOfWeek")), context)
+            .get(PropertyKey::from(js_str!("dayOfWeek")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -424,7 +424,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("dayOfYear")), context)
+            .get(PropertyKey::from(js_str!("dayOfYear")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -468,7 +468,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("weekOfYear")), context)
+            .get(PropertyKey::from(js_str!("weekOfYear")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -512,7 +512,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("yearOfWeek")), context)
+            .get(PropertyKey::from(js_str!("yearOfWeek")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -549,7 +549,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("daysInWeek")), context)
+            .get(PropertyKey::from(js_str!("daysInWeek")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -593,7 +593,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("daysInMonth")), context)
+            .get(PropertyKey::from(js_str!("daysInMonth")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
         let val = method
             .as_callable()
@@ -638,7 +638,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("daysInYear")), context)
+            .get(PropertyKey::from(js_str!("daysInYear")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -682,7 +682,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("monthsInYear")), context)
+            .get(PropertyKey::from(js_str!("monthsInYear")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -728,7 +728,7 @@ impl CalendarProtocol for JsObject {
         let date_like = date_like_to_object(date_like, context)?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("inLeapYear")), context)
+            .get(PropertyKey::from(js_str!("inLeapYear")), context)
             .expect("method must exist on a object that implements the CalendarProtocol.");
 
         let val = method
@@ -753,7 +753,7 @@ impl CalendarProtocol for JsObject {
         );
 
         let method = self
-            .get(PropertyKey::from(utf16!("fields")), context)
+            .get(PropertyKey::from(js_str!("fields")), context)
             .expect("method must exist on an object that implements the CalendarProtocol.");
 
         let result = method
@@ -799,7 +799,7 @@ impl CalendarProtocol for JsObject {
             .map_err(|e| TemporalError::general(e.to_string()))?;
 
         let method = self
-            .get(PropertyKey::from(utf16!("mergeFields")), context)
+            .get(PropertyKey::from(js_str!("mergeFields")), context)
             .expect("method must exist on an object that implements the CalendarProtocol.");
 
         let value = method
@@ -824,7 +824,7 @@ impl CalendarProtocol for JsObject {
     fn identifier(&self, context: &mut Context) -> TemporalResult<String> {
         let identifier = self
             .__get__(
-                &PropertyKey::from(utf16!("id")),
+                &PropertyKey::from(js_str!("id")),
                 self.clone().into(),
                 &mut context.into(),
             )

core/engine/src/builtins/temporal/duration/mod.rs

@@ -10,10 +10,11 @@ use crate::{
     object::internal_methods::get_prototype_from_constructor,
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsData, JsNativeError, JsObject, JsResult, JsString, JsSymbol, JsValue,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use temporal_rs::{
     components::Duration as InnerDuration,
@@ -108,73 +109,73 @@ impl IntrinsicObject for Duration {
                 Attribute::READONLY | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("years"),
+                js_string!("years"),
                 Some(get_years),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("months"),
+                js_string!("months"),
                 Some(get_months),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("weeks"),
+                js_string!("weeks"),
                 Some(get_weeks),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("days"),
+                js_string!("days"),
                 Some(get_days),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("hours"),
+                js_string!("hours"),
                 Some(get_hours),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("minutes"),
+                js_string!("minutes"),
                 Some(get_minutes),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("seconds"),
+                js_string!("seconds"),
                 Some(get_seconds),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("milliseconds"),
+                js_string!("milliseconds"),
                 Some(get_milliseconds),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("microseconds"),
+                js_string!("microseconds"),
                 Some(get_microseconds),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("nanoseconds"),
+                js_string!("nanoseconds"),
                 Some(get_nanoseconds),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("sign"),
+                js_string!("sign"),
                 Some(get_sign),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("blank"),
+                js_string!("blank"),
                 Some(is_blank),
                 None,
                 Attribute::CONFIGURABLE,
@@ -623,7 +624,7 @@ impl Duration {
                 let new_round_to = JsObject::with_null_proto();
                 // c. Perform ! CreateDataPropertyOrThrow(roundTo, "smallestUnit", paramString).
                 new_round_to.create_data_property_or_throw(
-                    utf16!("smallestUnit"),
+                    js_str!("smallestUnit"),
                     param_string,
                     context,
                 )?;
@@ -644,7 +645,7 @@ impl Duration {
         // 9. Let largestUnit be ? GetTemporalUnit(roundTo, "largestUnit", datetime, undefined, « "auto" »).
         let largest_unit = get_temporal_unit(
             &round_to,
-            utf16!("largestUnit"),
+            js_str!("largestUnit"),
             TemporalUnitGroup::DateTime,
             Some([TemporalUnit::Auto].into()),
             context,
@@ -661,12 +662,12 @@ impl Duration {
 
         // 14. Let roundingMode be ? ToTemporalRoundingMode(roundTo, "halfExpand").
         let rounding_mode =
-            get_option::<TemporalRoundingMode>(&round_to, utf16!("roundingMode"), context)?;
+            get_option::<TemporalRoundingMode>(&round_to, js_str!("roundingMode"), context)?;
 
         // 15. Let smallestUnit be ? GetTemporalUnit(roundTo, "smallestUnit", datetime, undefined).
         let smallest_unit = get_temporal_unit(
             &round_to,
-            utf16!("smallestUnit"),
+            js_str!("smallestUnit"),
             TemporalUnitGroup::DateTime,
             None,
             context,
@@ -725,7 +726,7 @@ impl Duration {
                 let total_of = JsObject::with_null_proto();
                 // c. Perform ! CreateDataPropertyOrThrow(totalOf, "unit", paramString).
                 total_of.create_data_property_or_throw(
-                    utf16!("unit"),
+                    js_str!("unit"),
                     param_string.clone(),
                     context,
                 )?;
@@ -748,7 +749,7 @@ impl Duration {
         // 10. Let unit be ? GetTemporalUnit(totalOf, "unit", datetime, required).
         let _unit = get_temporal_unit(
             &total_of,
-            utf16!("unit"),
+            js_str!("unit"),
             TemporalUnitGroup::DateTime,
             None,
             context,
@@ -905,70 +906,70 @@ pub(crate) fn to_temporal_partial_duration(
 
     // 3. NOTE: The following steps read properties and perform independent validation in alphabetical order.
     // 4. Let days be ? Get(temporalDurationLike, "days").
-    let days = unknown_object.get(utf16!("days"), context)?;
+    let days = unknown_object.get(js_str!("days"), context)?;
     if !days.is_undefined() {
         // 5. If days is not undefined, set result.[[Days]] to ? ToIntegerIfIntegral(days).
         result.set_days(f64::from(to_integer_if_integral(&days, context)?));
     }
 
     // 6. Let hours be ? Get(temporalDurationLike, "hours").
-    let hours = unknown_object.get(utf16!("hours"), context)?;
+    let hours = unknown_object.get(js_str!("hours"), context)?;
     // 7. If hours is not undefined, set result.[[Hours]] to ? ToIntegerIfIntegral(hours).
     if !hours.is_undefined() {
         result.set_hours(f64::from(to_integer_if_integral(&hours, context)?));
     }
 
     // 8. Let microseconds be ? Get(temporalDurationLike, "microseconds").
-    let microseconds = unknown_object.get(utf16!("microseconds"), context)?;
+    let microseconds = unknown_object.get(js_str!("microseconds"), context)?;
     // 9. If microseconds is not undefined, set result.[[Microseconds]] to ? ToIntegerIfIntegral(microseconds).
     if !microseconds.is_undefined() {
         result.set_microseconds(f64::from(to_integer_if_integral(&microseconds, context)?));
     }
 
     // 10. Let milliseconds be ? Get(temporalDurationLike, "milliseconds").
-    let milliseconds = unknown_object.get(utf16!("milliseconds"), context)?;
+    let milliseconds = unknown_object.get(js_str!("milliseconds"), context)?;
     // 11. If milliseconds is not undefined, set result.[[Milliseconds]] to ? ToIntegerIfIntegral(milliseconds).
     if !milliseconds.is_undefined() {
         result.set_milliseconds(f64::from(to_integer_if_integral(&milliseconds, context)?));
     }
 
     // 12. Let minutes be ? Get(temporalDurationLike, "minutes").
-    let minutes = unknown_object.get(utf16!("minutes"), context)?;
+    let minutes = unknown_object.get(js_str!("minutes"), context)?;
     // 13. If minutes is not undefined, set result.[[Minutes]] to ? ToIntegerIfIntegral(minutes).
     if !minutes.is_undefined() {
         result.set_minutes(f64::from(to_integer_if_integral(&minutes, context)?));
     }
 
     // 14. Let months be ? Get(temporalDurationLike, "months").
-    let months = unknown_object.get(utf16!("months"), context)?;
+    let months = unknown_object.get(js_str!("months"), context)?;
     // 15. If months is not undefined, set result.[[Months]] to ? ToIntegerIfIntegral(months).
     if !months.is_undefined() {
         result.set_months(f64::from(to_integer_if_integral(&months, context)?));
     }
 
     // 16. Let nanoseconds be ? Get(temporalDurationLike, "nanoseconds").
-    let nanoseconds = unknown_object.get(utf16!("nanoseconds"), context)?;
+    let nanoseconds = unknown_object.get(js_str!("nanoseconds"), context)?;
     // 17. If nanoseconds is not undefined, set result.[[Nanoseconds]] to ? ToIntegerIfIntegral(nanoseconds).
     if !nanoseconds.is_undefined() {
         result.set_nanoseconds(f64::from(to_integer_if_integral(&nanoseconds, context)?));
     }
 
     // 18. Let seconds be ? Get(temporalDurationLike, "seconds").
-    let seconds = unknown_object.get(utf16!("seconds"), context)?;
+    let seconds = unknown_object.get(js_str!("seconds"), context)?;
     // 19. If seconds is not undefined, set result.[[Seconds]] to ? ToIntegerIfIntegral(seconds).
     if !seconds.is_undefined() {
         result.set_seconds(f64::from(to_integer_if_integral(&seconds, context)?));
     }
 
     // 20. Let weeks be ? Get(temporalDurationLike, "weeks").
-    let weeks = unknown_object.get(utf16!("weeks"), context)?;
+    let weeks = unknown_object.get(js_str!("weeks"), context)?;
     // 21. If weeks is not undefined, set result.[[Weeks]] to ? ToIntegerIfIntegral(weeks).
     if !weeks.is_undefined() {
         result.set_weeks(f64::from(to_integer_if_integral(&weeks, context)?));
     }
 
     // 22. Let years be ? Get(temporalDurationLike, "years").
-    let years = unknown_object.get(utf16!("years"), context)?;
+    let years = unknown_object.get(js_str!("years"), context)?;
     // 23. If years is not undefined, set result.[[Years]] to ? ToIntegerIfIntegral(years).
     if !years.is_undefined() {
         result.set_years(f64::from(to_integer_if_integral(&years, context)?));

core/engine/src/builtins/temporal/instant/mod.rs

@@ -14,11 +14,12 @@ use crate::{
     object::internal_methods::get_prototype_from_constructor,
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsBigInt, JsData, JsNativeError, JsObject, JsResult, JsString, JsSymbol,
     JsValue,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use temporal_rs::{
     components::Instant as InnerInstant,
@@ -64,25 +65,25 @@ impl IntrinsicObject for Instant {
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("epochSeconds"),
+                js_str!("epochSeconds"),
                 Some(get_seconds),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("epochMilliseconds"),
+                js_str!("epochMilliseconds"),
                 Some(get_millis),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("epochMicroseconds"),
+                js_str!("epochMicroseconds"),
                 Some(get_micros),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("epochNanoseconds"),
+                js_str!("epochNanoseconds"),
                 Some(get_nanos),
                 None,
                 Attribute::CONFIGURABLE,
@@ -285,10 +286,10 @@ impl Instant {
 
         // Fetch the necessary options.
         let options = get_options_object(args.get_or_undefined(1))?;
-        let mode = get_option::<TemporalRoundingMode>(&options, utf16!("roundingMode"), context)?;
-        let increment = get_option::<f64>(&options, utf16!("roundingIncrement"), context)?;
-        let smallest_unit = get_option::<TemporalUnit>(&options, utf16!("smallestUnit"), context)?;
-        let largest_unit = get_option::<TemporalUnit>(&options, utf16!("largestUnit"), context)?;
+        let mode = get_option::<TemporalRoundingMode>(&options, js_str!("roundingMode"), context)?;
+        let increment = get_option::<f64>(&options, js_str!("roundingIncrement"), context)?;
+        let smallest_unit = get_option::<TemporalUnit>(&options, js_str!("smallestUnit"), context)?;
+        let largest_unit = get_option::<TemporalUnit>(&options, js_str!("largestUnit"), context)?;
         let result = instant
             .inner
             .until(&other, mode, increment, smallest_unit, largest_unit)?;
@@ -313,10 +314,10 @@ impl Instant {
         // 3. Return ? DifferenceTemporalInstant(since, instant, other, options).
         let other = to_temporal_instant(args.get_or_undefined(0))?;
         let options = get_options_object(args.get_or_undefined(1))?;
-        let mode = get_option::<TemporalRoundingMode>(&options, utf16!("roundingMode"), context)?;
-        let increment = get_option::<f64>(&options, utf16!("roundingIncrement"), context)?;
-        let smallest_unit = get_option::<TemporalUnit>(&options, utf16!("smallestUnit"), context)?;
-        let largest_unit = get_option::<TemporalUnit>(&options, utf16!("largestUnit"), context)?;
+        let mode = get_option::<TemporalRoundingMode>(&options, js_str!("roundingMode"), context)?;
+        let increment = get_option::<f64>(&options, js_str!("roundingIncrement"), context)?;
+        let smallest_unit = get_option::<TemporalUnit>(&options, js_str!("smallestUnit"), context)?;
+        let largest_unit = get_option::<TemporalUnit>(&options, js_str!("largestUnit"), context)?;
         let result = instant
             .inner
             .since(&other, mode, increment, smallest_unit, largest_unit)?;
@@ -353,7 +354,7 @@ impl Instant {
                 let new_round_to = JsObject::with_null_proto();
                 // c. Perform ! CreateDataPropertyOrThrow(roundTo, "smallestUnit", paramString).
                 new_round_to.create_data_property_or_throw(
-                    utf16!("smallestUnit"),
+                    js_str!("smallestUnit"),
                     param_string,
                     context,
                 )?;
@@ -370,16 +371,16 @@ impl Instant {
         // alphabetical order (ToTemporalRoundingIncrement reads "roundingIncrement" and ToTemporalRoundingMode reads "roundingMode").
         // 7. Let roundingIncrement be ? ToTemporalRoundingIncrement(roundTo).
         let rounding_increment =
-            get_option::<f64>(&round_to, utf16!("roundingIncrement"), context)?;
+            get_option::<f64>(&round_to, js_str!("roundingIncrement"), context)?;
 
         // 8. Let roundingMode be ? ToTemporalRoundingMode(roundTo, "halfExpand").
         let rounding_mode =
-            get_option::<TemporalRoundingMode>(&round_to, utf16!("roundingMode"), context)?;
+            get_option::<TemporalRoundingMode>(&round_to, js_str!("roundingMode"), context)?;
 
         // 9. Let smallestUnit be ? GetTemporalUnit(roundTo, "smallestUnit"), time, required).
         let smallest_unit = get_temporal_unit(
             &round_to,
-            utf16!("smallestUnit"),
+            js_str!("smallestUnit"),
             TemporalUnitGroup::Time,
             None,
             context,

core/engine/src/builtins/temporal/mod.rs

@@ -37,7 +37,7 @@ use crate::{
     value::Type,
     Context, JsBigInt, JsError, JsNativeError, JsObject, JsResult, JsString, JsSymbol, JsValue,
 };
-use boa_macros::utf16;
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use temporal_rs::{
     components::{Date as TemporalDate, ZonedDateTime as TemporalZonedDateTime},
@@ -252,7 +252,7 @@ pub(crate) fn to_relative_temporal_object(
     options: &JsObject,
     context: &mut Context,
 ) -> RelativeTemporalObjectResult {
-    let relative_to = options.get(PropertyKey::from(utf16!("relativeTo")), context)?;
+    let relative_to = options.get(PropertyKey::from(js_str!("relativeTo")), context)?;
     let plain_date = match relative_to {
         JsValue::String(relative_to_str) => Some(relative_to_str.into()),
         JsValue::Object(relative_to_obj) => Some(relative_to_obj.into()),

core/engine/src/builtins/temporal/options.rs

@@ -10,7 +10,9 @@
 
 use crate::{
     builtins::options::{get_option, ParsableOptionType},
-    js_string, Context, JsNativeError, JsObject, JsResult,
+    js_string,
+    string::JsStr,
+    Context, JsNativeError, JsObject, JsResult,
 };
 use temporal_rs::options::{
     ArithmeticOverflow, DurationOverflow, InstantDisambiguation, OffsetDisambiguation,
@@ -58,7 +60,7 @@ pub(crate) fn get_temporal_rounding_increment(
 #[inline]
 pub(crate) fn get_temporal_unit(
     options: &JsObject,
-    key: &[u16],
+    key: JsStr<'_>,
     unit_group: TemporalUnitGroup,
     extra_values: Option<Vec<TemporalUnit>>,
     context: &mut Context,

core/engine/src/builtins/temporal/plain_date/mod.rs

@@ -13,10 +13,11 @@ use crate::{
     object::internal_methods::get_prototype_from_constructor,
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsData, JsNativeError, JsObject, JsResult, JsString, JsSymbol, JsValue,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use temporal_rs::{
     components::{
@@ -125,80 +126,85 @@ impl IntrinsicObject for PlainDate {
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("calendarId"),
+                js_string!("calendarId"),
                 Some(get_calendar_id),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("year"),
+                js_string!("year"),
                 Some(get_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("month"),
+                js_string!("month"),
                 Some(get_month),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("monthCode"),
+                js_string!("monthCode"),
                 Some(get_month_code),
                 None,
                 Attribute::CONFIGURABLE,
             )
-            .accessor(utf16!("day"), Some(get_day), None, Attribute::CONFIGURABLE)
             .accessor(
-                utf16!("dayOfWeek"),
+                js_string!("day"),
+                Some(get_day),
+                None,
+                Attribute::CONFIGURABLE,
+            )
+            .accessor(
+                js_string!("dayOfWeek"),
                 Some(get_day_of_week),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("dayOfYear"),
+                js_string!("dayOfYear"),
                 Some(get_day_of_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("weekOfYear"),
+                js_string!("weekOfYear"),
                 Some(get_week_of_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("yearOfWeek"),
+                js_string!("yearOfWeek"),
                 Some(get_year_of_week),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("daysInWeek"),
+                js_string!("daysInWeek"),
                 Some(get_days_in_week),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("daysInMonth"),
+                js_string!("daysInMonth"),
                 Some(get_days_in_month),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("daysInYear"),
+                js_string!("daysInYear"),
                 Some(get_days_in_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("monthsInYear"),
+                js_string!("monthsInYear"),
                 Some(get_months_in_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("inLeapYear"),
+                js_string!("inLeapYear"),
                 Some(get_in_leap_year),
                 None,
                 Attribute::CONFIGURABLE,
@@ -643,7 +649,7 @@ pub(crate) fn to_temporal_date(
             // c. If item has an [[InitializedTemporalDateTime]] internal slot, then
         } else if let Some(date_time) = object.downcast_ref::<PlainDateTime>() {
             // i. Perform ? ToTemporalOverflow(options).
-            let _o = get_option(&options_obj, utf16!("overflow"), context)?
+            let _o = get_option(&options_obj, js_str!("overflow"), context)?
                 .unwrap_or(ArithmeticOverflow::Constrain);
 
             let date = InnerDate::from_datetime(date_time.inner());

core/engine/src/builtins/temporal/plain_date_time/mod.rs

@@ -11,10 +11,11 @@ use crate::{
     object::internal_methods::get_prototype_from_constructor,
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsData, JsNativeError, JsObject, JsResult, JsString, JsSymbol, JsValue,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 #[cfg(test)]
@@ -152,116 +153,116 @@ impl IntrinsicObject for PlainDateTime {
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("calendarId"),
+                js_str!("calendarId"),
                 Some(get_calendar_id),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("year"),
+                js_str!("year"),
                 Some(get_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("month"),
+                js_str!("month"),
                 Some(get_month),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("monthCode"),
+                js_str!("monthCode"),
                 Some(get_month_code),
                 None,
                 Attribute::CONFIGURABLE,
             )
-            .accessor(utf16!("day"), Some(get_day), None, Attribute::CONFIGURABLE)
+            .accessor(js_str!("day"), Some(get_day), None, Attribute::CONFIGURABLE)
             .accessor(
-                utf16!("hour"),
+                js_str!("hour"),
                 Some(get_hour),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("minute"),
+                js_str!("minute"),
                 Some(get_minute),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("second"),
+                js_str!("second"),
                 Some(get_second),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("millisecond"),
+                js_str!("millisecond"),
                 Some(get_millisecond),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("microsecond"),
+                js_str!("microsecond"),
                 Some(get_microsecond),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("nanosecond"),
+                js_str!("nanosecond"),
                 Some(get_nanosecond),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("dayOfWeek"),
+                js_str!("dayOfWeek"),
                 Some(get_day_of_week),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("dayOfYear"),
+                js_str!("dayOfYear"),
                 Some(get_day_of_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("weekOfYear"),
+                js_str!("weekOfYear"),
                 Some(get_week_of_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("yearOfWeek"),
+                js_str!("yearOfWeek"),
                 Some(get_year_of_week),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("daysInWeek"),
+                js_str!("daysInWeek"),
                 Some(get_days_in_week),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("daysInMonth"),
+                js_str!("daysInMonth"),
                 Some(get_days_in_month),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("daysInYear"),
+                js_str!("daysInYear"),
                 Some(get_days_in_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("monthsInYear"),
+                js_str!("monthsInYear"),
                 Some(get_months_in_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("inLeapYear"),
+                js_str!("inLeapYear"),
                 Some(get_in_leap_year),
                 None,
                 Attribute::CONFIGURABLE,

core/engine/src/builtins/temporal/plain_time/mod.rs

@@ -14,7 +14,7 @@ use crate::{
     Context, JsArgs, JsData, JsNativeError, JsObject, JsResult, JsString, JsSymbol, JsValue,
 };
 use boa_gc::{Finalize, Trace};
-use boa_macros::utf16;
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 use temporal_rs::{
     components::Time,
@@ -71,33 +71,38 @@ impl IntrinsicObject for PlainTime {
                 Self::NAME,
                 Attribute::CONFIGURABLE,
             )
-            .accessor(utf16!("hour"), Some(get_hour), None, Attribute::default())
             .accessor(
-                utf16!("minute"),
+                js_string!("hour"),
+                Some(get_hour),
+                None,
+                Attribute::default(),
+            )
+            .accessor(
+                js_string!("minute"),
                 Some(get_minute),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("second"),
+                js_string!("second"),
                 Some(get_second),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("millisecond"),
+                js_string!("millisecond"),
                 Some(get_millisecond),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("microsecond"),
+                js_string!("microsecond"),
                 Some(get_microsecond),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("nanosecond"),
+                js_string!("nanosecond"),
                 Some(get_nanosecond),
                 None,
                 Attribute::CONFIGURABLE,
@@ -345,7 +350,7 @@ impl PlainTime {
                 let new_round_to = JsObject::with_null_proto();
                 // c. Perform ! CreateDataPropertyOrThrow(roundTo, "smallestUnit", paramString).
                 new_round_to.create_data_property_or_throw(
-                    utf16!("smallestUnit"),
+                    js_str!("smallestUnit"),
                     param_string,
                     context,
                 )?;
@@ -361,16 +366,16 @@ impl PlainTime {
         // 6. NOTE: The following steps read options and perform independent validation in alphabetical order (ToTemporalRoundingIncrement reads "roundingIncrement" and ToTemporalRoundingMode reads "roundingMode").
         // 7. Let roundingIncrement be ? ToTemporalRoundingIncrement(roundTo).
         let rounding_increment =
-            get_option::<f64>(&round_to, utf16!("roundingIncrement"), context)?;
+            get_option::<f64>(&round_to, js_str!("roundingIncrement"), context)?;
 
         // 8. Let roundingMode be ? ToTemporalRoundingMode(roundTo, "halfExpand").
         let rounding_mode =
-            get_option::<TemporalRoundingMode>(&round_to, utf16!("roundingMode"), context)?;
+            get_option::<TemporalRoundingMode>(&round_to, js_str!("roundingMode"), context)?;
 
         // 9. Let smallestUnit be ? GetTemporalUnit(roundTo, "smallestUnit", time, required).
         let smallest_unit = get_temporal_unit(
             &round_to,
-            utf16!("smallestUnit"),
+            js_str!("smallestUnit"),
             TemporalUnitGroup::Time,
             None,
             context,
@@ -404,29 +409,29 @@ impl PlainTime {
         let fields = JsObject::with_object_proto(context.intrinsics());
 
         // 4. Perform ! CreateDataPropertyOrThrow(fields, "isoHour", 𝔽(temporalTime.[[ISOHour]])).
-        fields.create_data_property_or_throw(utf16!("isoHour"), time.inner.hour(), context)?;
+        fields.create_data_property_or_throw(js_str!("isoHour"), time.inner.hour(), context)?;
         // 5. Perform ! CreateDataPropertyOrThrow(fields, "isoMicrosecond", 𝔽(temporalTime.[[ISOMicrosecond]])).
         fields.create_data_property_or_throw(
-            utf16!("isoMicrosecond"),
+            js_str!("isoMicrosecond"),
             time.inner.microsecond(),
             context,
         )?;
         // 6. Perform ! CreateDataPropertyOrThrow(fields, "isoMillisecond", 𝔽(temporalTime.[[ISOMillisecond]])).
         fields.create_data_property_or_throw(
-            utf16!("isoMillisecond"),
+            js_str!("isoMillisecond"),
             time.inner.millisecond(),
             context,
         )?;
         // 7. Perform ! CreateDataPropertyOrThrow(fields, "isoMinute", 𝔽(temporalTime.[[ISOMinute]])).
-        fields.create_data_property_or_throw(utf16!("isoMinute"), time.inner.minute(), context)?;
+        fields.create_data_property_or_throw(js_str!("isoMinute"), time.inner.minute(), context)?;
         // 8. Perform ! CreateDataPropertyOrThrow(fields, "isoNanosecond", 𝔽(temporalTime.[[ISONanosecond]])).
         fields.create_data_property_or_throw(
-            utf16!("isoNanosecond"),
+            js_str!("isoNanosecond"),
             time.inner.nanosecond(),
             context,
         )?;
         // 9. Perform ! CreateDataPropertyOrThrow(fields, "isoSecond", 𝔽(temporalTime.[[ISOSecond]])).
-        fields.create_data_property_or_throw(utf16!("isoSecond"), time.inner.second(), context)?;
+        fields.create_data_property_or_throw(js_str!("isoSecond"), time.inner.second(), context)?;
 
         // 10. Return fields.
         Ok(fields.into())

core/engine/src/builtins/temporal/plain_year_month/mod.rs

@@ -7,7 +7,7 @@ use crate::{
     object::internal_methods::get_prototype_from_constructor,
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsData, JsNativeError, JsObject, JsResult, JsString, JsSymbol, JsValue,
 };
 use boa_gc::{Finalize, Trace};
@@ -98,49 +98,49 @@ impl IntrinsicObject for PlainYearMonth {
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("calendarId"),
+                js_string!("calendarId"),
                 Some(get_calendar_id),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("year"),
+                js_string!("year"),
                 Some(get_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("month"),
+                js_string!("month"),
                 Some(get_month),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("monthCode"),
+                js_string!("monthCode"),
                 Some(get_month_code),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("daysInMonth"),
+                js_string!("daysInMonth"),
                 Some(get_days_in_month),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("daysInYear"),
+                js_string!("daysInYear"),
                 Some(get_days_in_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("monthsInYear"),
+                js_string!("monthsInYear"),
                 Some(get_months_in_year),
                 None,
                 Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("inLeapYear"),
+                js_string!("inLeapYear"),
                 Some(get_in_leap_year),
                 None,
                 Attribute::CONFIGURABLE,

core/engine/src/builtins/temporal/tests.rs

@@ -1,4 +1,6 @@
-use crate::{js_string, run_test_actions, JsValue, TestAction};
+use boa_macros::js_str;
+
+use crate::{run_test_actions, JsValue, TestAction};
 
 // Temporal Object tests.
 
@@ -8,9 +10,9 @@ fn temporal_object() {
     run_test_actions([
         TestAction::assert_eq(
             "Object.prototype.toString.call(Temporal)",
-            js_string!("[object Temporal]"),
+            js_str!("[object Temporal]"),
         ),
-        TestAction::assert_eq("String(Temporal)", js_string!("[object Temporal]")),
+        TestAction::assert_eq("String(Temporal)", js_str!("[object Temporal]")),
         TestAction::assert_eq("Object.keys(Temporal).length === 0", true),
     ]);
 }
@@ -22,7 +24,7 @@ fn now_object() {
         TestAction::assert_eq("Object.isExtensible(Temporal.Now)", true),
         TestAction::assert_eq(
             "Object.prototype.toString.call(Temporal.Now)",
-            js_string!("[object Temporal.Now]"),
+            js_str!("[object Temporal.Now]"),
         ),
         TestAction::assert_eq(
             "Object.getPrototypeOf(Temporal.Now) === Object.prototype",

core/engine/src/builtins/temporal/time_zone/custom.rs

@@ -1,7 +1,8 @@
 //! A custom `TimeZone` object.
-use crate::{property::PropertyKey, string::utf16, Context, JsObject, JsValue};
+use crate::{property::PropertyKey, Context, JsObject, JsValue};
 
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use num_bigint::BigInt;
 use temporal_rs::{
     components::{tz::TzProtocol, Instant},
@@ -18,7 +19,7 @@ impl TzProtocol for JsCustomTimeZone {
     fn get_offset_nanos_for(&self, context: &mut Context) -> TemporalResult<BigInt> {
         let method = self
             .tz
-            .get(utf16!("getOffsetNanosFor"), context)
+            .get(js_str!("getOffsetNanosFor"), context)
             .expect("Method must exist for the custom calendar to be valid.");
 
         let result = method
@@ -45,7 +46,7 @@ impl TzProtocol for JsCustomTimeZone {
         let ident = self
             .tz
             .__get__(
-                &PropertyKey::from(utf16!("id")),
+                &PropertyKey::from(js_str!("id")),
                 JsValue::undefined(),
                 &mut context.into(),
             )

core/engine/src/builtins/temporal/time_zone/mod.rs

@@ -11,7 +11,7 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, CONSTRUCTOR},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     Context, JsArgs, JsData, JsNativeError, JsObject, JsResult, JsString, JsSymbol, JsValue,
 };
 use boa_gc::{custom_trace, Finalize, Trace};
@@ -95,7 +95,7 @@ impl IntrinsicObject for TimeZone {
                 realm.intrinsics().constructors().time_zone().prototype(),
                 Attribute::default(),
             )
-            .accessor(utf16!("id"), Some(get_id), None, Attribute::default())
+            .accessor(js_string!("id"), Some(get_id), None, Attribute::default())
             .build();
     }
 

core/engine/src/builtins/typed_array/builtin.rs

@@ -3,7 +3,7 @@ use std::{
     sync::atomic::{self, Ordering},
 };
 
-use boa_macros::utf16;
+use boa_macros::{js_str, utf16};
 use num_traits::Zero;
 
 use super::{
@@ -79,19 +79,19 @@ impl IntrinsicObject for BuiltinTypedArray {
                 Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
             )
             .accessor(
-                utf16!("buffer"),
+                js_string!("buffer"),
                 Some(get_buffer),
                 None,
                 Attribute::CONFIGURABLE | Attribute::NON_ENUMERABLE,
             )
             .accessor(
-                utf16!("byteLength"),
+                js_string!("byteLength"),
                 Some(get_byte_length),
                 None,
                 Attribute::CONFIGURABLE | Attribute::NON_ENUMERABLE,
             )
             .accessor(
-                utf16!("byteOffset"),
+                js_string!("byteOffset"),
                 Some(get_byte_offset),
                 None,
                 Attribute::CONFIGURABLE | Attribute::NON_ENUMERABLE,
@@ -1214,7 +1214,7 @@ impl BuiltinTypedArray {
         for k in 0..len {
             // a. If k > 0, set R to the string-concatenation of R and sep.
             if k > 0 {
-                r.extend_from_slice(&sep);
+                r.extend(sep.iter());
             }
 
             // b. Let element be ! Get(O, ! ToString(𝔽(k))).
@@ -1223,12 +1223,12 @@ impl BuiltinTypedArray {
             // c. If element is undefined, let next be the empty String; otherwise, let next be ! ToString(element).
             // d. Set R to the string-concatenation of R and next.
             if !element.is_undefined() {
-                r.extend_from_slice(&element.to_string(context)?);
+                r.extend(element.to_string(context)?.iter());
             }
         }
 
         // 9. Return R.
-        Ok(js_string!(r).into())
+        Ok(js_string!(&r[..]).into())
     }
 
     /// `%TypedArray%.prototype.keys ( )`
@@ -2493,7 +2493,7 @@ impl BuiltinTypedArray {
             if is_fixed_len || !next_element.is_undefined() {
                 let s = next_element
                     .invoke(
-                        utf16!("toLocaleString"),
+                        js_str!("toLocaleString"),
                         &[
                             args.get_or_undefined(0).clone(),
                             args.get_or_undefined(1).clone(),
@@ -2502,11 +2502,11 @@ impl BuiltinTypedArray {
                     )?
                     .to_string(context)?;
 
-                r.extend_from_slice(&s);
+                r.extend(s.iter());
             };
         }
 
-        Ok(js_string!(r).into())
+        Ok(js_string!(&r[..]).into())
     }
 
     /// `%TypedArray%.prototype.values ( )`

core/engine/src/builtins/typed_array/mod.rs

@@ -29,6 +29,7 @@ use crate::{
     Context, JsArgs, JsResult, JsString,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 mod builtin;
@@ -74,12 +75,12 @@ impl<T: TypedArrayMarker> IntrinsicObject for T {
                 Attribute::CONFIGURABLE,
             )
             .property(
-                js_string!("BYTES_PER_ELEMENT"),
+                js_str!("BYTES_PER_ELEMENT"),
                 std::mem::size_of::<T::Element>(),
                 Attribute::READONLY | Attribute::NON_ENUMERABLE | Attribute::PERMANENT,
             )
             .static_property(
-                js_string!("BYTES_PER_ELEMENT"),
+                js_str!("BYTES_PER_ELEMENT"),
                 std::mem::size_of::<T::Element>(),
                 Attribute::READONLY | Attribute::NON_ENUMERABLE | Attribute::PERMANENT,
             )

core/engine/src/builtins/typed_array/object.rs

@@ -16,7 +16,7 @@ use crate::{
     Context, JsNativeError, JsResult, JsString, JsValue,
 };
 use boa_gc::{Finalize, Trace};
-use boa_macros::utf16;
+use boa_macros::js_str;
 
 use super::{is_valid_integer_index, TypedArrayKind};
 
@@ -263,7 +263,7 @@ impl TypedArray {
 /// [spec]: https://tc39.es/ecma262/#sec-canonicalnumericindexstring
 fn canonical_numeric_index_string(argument: &JsString) -> Option<f64> {
     // 1. If argument is "-0", return -0𝔽.
-    if argument == utf16!("-0") {
+    if argument == &js_str!("-0") {
         return Some(-0.0);
     }
 

core/engine/src/builtins/uri/mod.rs

@@ -305,11 +305,11 @@ where
     loop {
         // a. If k = strLen, return R.
         if k == str_len {
-            return Ok(js_string!(r));
+            return Ok(js_string!(&r[..]));
         }
 
         // b. Let C be the code unit at index k within string.
-        let c = string[k];
+        let c = string.get_expect(k);
 
         // c. If C is in unescapedSet, then
         if unescaped_set(c) {
@@ -380,11 +380,11 @@ where
     loop {
         // a. If k = strLen, return R.
         if k == str_len {
-            return Ok(js_string!(r));
+            return Ok(js_string!(&r[..]));
         }
 
         // b. Let C be the code unit at index k within string.
-        let c = string[k];
+        let c = string.get_expect(k);
 
         // c. If C is not the code unit 0x0025 (PERCENT SIGN), then
         #[allow(clippy::if_not_else)]
@@ -406,9 +406,10 @@ where
             // iii. If the code units at index (k + 1) and (k + 2) within string do not represent
             // hexadecimal digits, throw a URIError exception.
             // iv. Let B be the 8-bit value represented by the two hexadecimal digits at index (k + 1) and (k + 2).
-            let b = decode_hex_byte(string[k + 1], string[k + 2]).ok_or_else(|| {
-                JsNativeError::uri().with_message("invalid hexadecimal digit found")
-            })?;
+            let b = decode_hex_byte(string.get_expect(k + 1), string.get_expect(k + 2))
+                .ok_or_else(|| {
+                    JsNativeError::uri().with_message("invalid hexadecimal digit found")
+                })?;
 
             // v. Set k to k + 2.
             k += 2;
@@ -428,7 +429,7 @@ where
                 } else {
                     // 3. Else,
                     // a. Let S be the substring of string from start to k + 1.
-                    Vec::from(&string[start..=k])
+                    string.get_expect(start..=k).to_vec()
                 }
             } else {
                 // viii. Else,
@@ -456,7 +457,7 @@ where
                     k += 1;
 
                     // b. If the code unit at index k within string is not the code unit 0x0025 (PERCENT SIGN), throw a URIError exception.
-                    if string[k] != 0x0025 {
+                    if string.get_expect(k) != 0x0025 {
                         return Err(JsNativeError::uri()
                             .with_message("escape characters must be preceded with a % sign")
                             .into());
@@ -464,9 +465,10 @@ where
 
                     // c. If the code units at index (k + 1) and (k + 2) within string do not represent hexadecimal digits, throw a URIError exception.
                     // d. Let B be the 8-bit value represented by the two hexadecimal digits at index (k + 1) and (k + 2).
-                    let b = decode_hex_byte(string[k + 1], string[k + 2]).ok_or_else(|| {
-                        JsNativeError::uri().with_message("invalid hexadecimal digit found")
-                    })?;
+                    let b = decode_hex_byte(string.get_expect(k + 1), string.get_expect(k + 2))
+                        .ok_or_else(|| {
+                            JsNativeError::uri().with_message("invalid hexadecimal digit found")
+                        })?;
 
                     // e. Set k to k + 2.
                     k += 2;

core/engine/src/builtins/weak_map/mod.rs

@@ -17,11 +17,12 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, ErasedVTableObject, JsObject},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     symbol::JsSymbol,
     Context, JsArgs, JsNativeError, JsResult, JsString, JsValue,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 type NativeWeakMap = boa_gc::WeakMap<ErasedVTableObject, JsValue>;
@@ -100,7 +101,7 @@ impl BuiltInConstructor for WeakMap {
         }
 
         // 5. Let adder be ? Get(map, "set").
-        let adder = map.get(utf16!("set"), context)?;
+        let adder = map.get(js_str!("set"), context)?;
 
         // 6. If IsCallable(adder) is false, throw a TypeError exception.
         if !adder.is_callable() {

core/engine/src/builtins/weak_set/mod.rs

@@ -14,11 +14,12 @@ use crate::{
     object::{internal_methods::get_prototype_from_constructor, ErasedVTableObject, JsObject},
     property::Attribute,
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
+    string::common::StaticJsStrings,
     symbol::JsSymbol,
     Context, JsArgs, JsNativeError, JsResult, JsString, JsValue,
 };
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use boa_profiler::Profiler;
 
 type NativeWeakSet = boa_gc::WeakMap<ErasedVTableObject, ()>;
@@ -96,7 +97,7 @@ impl BuiltInConstructor for WeakSet {
         }
 
         // 5. Let adder be ? Get(set, "add").
-        let adder = weak_set.get(utf16!("add"), context)?;
+        let adder = weak_set.get(js_str!("add"), context)?;
 
         // 6. If IsCallable(adder) is false, throw a TypeError exception.
         let adder = adder

core/engine/src/bytecompiler/declarations.rs

@@ -18,7 +18,7 @@ use boa_ast::{
     visitor::NodeRef,
     Declaration, Script, StatementListItem,
 };
-use boa_interner::Sym;
+use boa_interner::{JStrRef, Sym};
 
 #[cfg(feature = "annex-b")]
 use boa_ast::operations::annex_b_function_declarations_names;
@@ -223,9 +223,11 @@ pub(crate) fn eval_declaration_instantiation_context(
     let private_identifiers = private_identifiers
         .into_iter()
         .map(|ident| {
+            // TODO: Replace JStrRef with JsStr this would eliminate the to_vec call.
+            let ident = ident.to_vec();
             context
                 .interner()
-                .get(ident.as_slice())
+                .get(JStrRef::Utf16(&ident))
                 .expect("string should be in interner")
         })
         .collect();

core/engine/src/bytecompiler/expression/mod.rs

@@ -4,7 +4,7 @@ mod object_literal;
 mod unary;
 mod update;
 
-use super::{Access, Callable, NodeKind, Operand};
+use super::{Access, Callable, NodeKind, Operand, ToJsString};
 use crate::{
     bytecompiler::{ByteCompiler, Literal},
     vm::{GeneratorResumeKind, Opcode},
@@ -22,9 +22,9 @@ use boa_ast::{
 impl ByteCompiler<'_> {
     fn compile_literal(&mut self, lit: &AstLiteral, use_expr: bool) {
         match lit {
-            AstLiteral::String(v) => self.emit_push_literal(Literal::String(
-                self.interner().resolve_expect(*v).into_common(false),
-            )),
+            AstLiteral::String(v) => {
+                self.emit_push_literal(Literal::String(v.to_js_string(self.interner())));
+            }
             AstLiteral::Int(v) => self.emit_push_integer(*v),
             AstLiteral::Num(v) => self.emit_push_rational(*v),
             AstLiteral::BigInt(v) => {
@@ -58,9 +58,9 @@ impl ByteCompiler<'_> {
     fn compile_template_literal(&mut self, template_literal: &TemplateLiteral, use_expr: bool) {
         for element in template_literal.elements() {
             match element {
-                TemplateElement::String(s) => self.emit_push_literal(Literal::String(
-                    self.interner().resolve_expect(*s).into_common(false),
-                )),
+                TemplateElement::String(s) => {
+                    self.emit_push_literal(Literal::String(s.to_js_string(self.interner())));
+                }
                 TemplateElement::Expr(expr) => {
                     self.compile_expr(expr, true);
                 }
@@ -268,14 +268,12 @@ impl ByteCompiler<'_> {
                 for (cooked, raw) in template.cookeds().iter().zip(template.raws()) {
                     if let Some(cooked) = cooked {
                         self.emit_push_literal(Literal::String(
-                            self.interner().resolve_expect(*cooked).into_common(false),
+                            cooked.to_js_string(self.interner()),
                         ));
                     } else {
                         self.emit_opcode(Opcode::PushUndefined);
                     }
-                    self.emit_push_literal(Literal::String(
-                        self.interner().resolve_expect(*raw).into_common(false),
-                    ));
+                    self.emit_push_literal(Literal::String(raw.to_js_string(self.interner())));
                 }
 
                 self.emit(

core/engine/src/bytecompiler/mod.rs

@@ -21,7 +21,7 @@ use crate::{
         BindingOpcode, CodeBlock, CodeBlockFlags, Constant, GeneratorResumeKind, Handler,
         InlineCache, Opcode, VaryingOperandKind,
     },
-    JsBigInt, JsString,
+    JsBigInt, JsStr, JsString,
 };
 use boa_ast::{
     declaration::{Binding, LexicalDeclaration, VarDeclaration},
@@ -55,7 +55,15 @@ pub(crate) trait ToJsString {
 
 impl ToJsString for Sym {
     fn to_js_string(&self, interner: &Interner) -> JsString {
-        js_string!(interner.resolve_expect(*self).utf16())
+        // TODO: Identify latin1 encodeable strings during parsing to avoid this check.
+        let string = interner.resolve_expect(*self).utf16();
+        for c in string {
+            if u8::try_from(*c).is_err() {
+                return js_string!(string);
+            }
+        }
+        let string = string.iter().map(|c| *c as u8).collect::<Vec<_>>();
+        js_string!(JsStr::latin1(&string))
     }
 }
 
@@ -392,9 +400,9 @@ impl<'ctx> ByteCompiler<'ctx> {
             return *index;
         }
 
-        let string = self.interner().resolve_expect(name.sym()).utf16();
         let index = self.constants.len() as u32;
-        self.constants.push(Constant::String(js_string!(string)));
+        let string = name.to_js_string(self.interner());
+        self.constants.push(Constant::String(string));
         self.names_map.insert(name, index);
         index
     }
@@ -744,7 +752,7 @@ impl<'ctx> ByteCompiler<'ctx> {
     }
 
     fn resolve_identifier_expect(&self, identifier: Identifier) -> JsString {
-        js_string!(self.interner().resolve_expect(identifier.sym()).utf16())
+        identifier.to_js_string(self.interner())
     }
 
     fn access_get(&mut self, access: Access<'_>, use_expr: bool) {

core/engine/src/class.rs

@@ -10,7 +10,7 @@
 //! #    property::Attribute,
 //! #    class::{Class, ClassBuilder},
 //! #    Context, JsResult, JsValue,
-//! #    JsArgs, Source, JsObject, js_string,
+//! #    JsArgs, Source, JsObject, js_str, js_string,
 //! #    JsNativeError, JsData,
 //! # };
 //! # use boa_gc::{Finalize, Trace};
@@ -56,7 +56,7 @@
 //!         let age = args.get_or_undefined(1).to_number(context)?;
 //!
 //!         // Roughly equivalent to `this.age = Number(age)`.
-//!         instance.set(js_string!("age"), age, true, context)?;
+//!         instance.set(js_str!("age"), age, true, context)?;
 //!
 //!         Ok(())
 //!     }
@@ -70,9 +70,9 @@
 //!                 if let Some(object) = this.as_object() {
 //!                     if let Some(animal) = object.downcast_ref::<Animal>() {
 //!                         return Ok(match &*animal {
-//!                             Self::Cat => js_string!("meow"),
-//!                             Self::Dog => js_string!("woof"),
-//!                             Self::Other => js_string!(r"¯\_(ツ)_/¯"),
+//!                             Self::Cat => js_str!("meow"),
+//!                             Self::Dog => js_str!("woof"),
+//!                             Self::Other => js_str!(r"¯\_(ツ)_/¯"),
 //!                         }.into());
 //!                     }
 //!                 }
@@ -96,7 +96,7 @@
 //!
 //!     assert_eq!(
 //!         result.as_string().unwrap(),
-//!         &js_string!("My pet is 3 years old. Right, buddy? - woof!")
+//!         &js_str!("My pet is 3 years old. Right, buddy? - woof!")
 //!     );
 //! }
 //! ```

core/engine/src/context/intrinsics.rs

@@ -1,6 +1,7 @@
 //! Data structures that contain intrinsic objects and constructors.
 
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 
 use crate::{
     builtins::{iterable::IteratorPrototypes, uri::UriFunctions, Array, OrdinaryObject},
@@ -1394,7 +1395,7 @@ impl ObjectTemplates {
         let ordinary_object =
             ObjectTemplate::with_prototype(root_shape, constructors.object().prototype());
         let mut array = ObjectTemplate::new(root_shape);
-        let length_property_key: PropertyKey = js_string!("length").into();
+        let length_property_key: PropertyKey = js_str!("length").into();
         array.property(
             length_property_key.clone(),
             Attribute::WRITABLE | Attribute::PERMANENT | Attribute::NON_ENUMERABLE,
@@ -1419,7 +1420,7 @@ impl ObjectTemplates {
         let mut regexp = regexp_without_proto.clone();
         regexp.set_prototype(constructors.regexp().prototype());
 
-        let name_property_key: PropertyKey = js_string!("name").into();
+        let name_property_key: PropertyKey = js_str!("name").into();
         let mut function = ObjectTemplate::new(root_shape);
         function.property(
             length_property_key.clone(),
@@ -1478,7 +1479,7 @@ impl ObjectTemplates {
         // [[Get]]: %ThrowTypeError%, [[Set]]: %ThrowTypeError%, [[Enumerable]]: false,
         // [[Configurable]]: false }).
         unmapped_arguments.accessor(
-            js_string!("callee").into(),
+            js_str!("callee").into(),
             true,
             true,
             Attribute::NON_ENUMERABLE | Attribute::PERMANENT,
@@ -1487,17 +1488,17 @@ impl ObjectTemplates {
         // 21. Perform ! DefinePropertyOrThrow(obj, "callee", PropertyDescriptor {
         // [[Value]]: func, [[Writable]]: true, [[Enumerable]]: false, [[Configurable]]: true }).
         mapped_arguments.property(
-            js_string!("callee").into(),
+            js_str!("callee").into(),
             Attribute::WRITABLE | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
         );
 
         let mut iterator_result = ordinary_object.clone();
         iterator_result.property(
-            js_string!("value").into(),
+            js_str!("value").into(),
             Attribute::WRITABLE | Attribute::CONFIGURABLE | Attribute::ENUMERABLE,
         );
         iterator_result.property(
-            js_string!("done").into(),
+            js_str!("done").into(),
             Attribute::WRITABLE | Attribute::CONFIGURABLE | Attribute::ENUMERABLE,
         );
 
@@ -1509,11 +1510,11 @@ impl ObjectTemplates {
 
             with_resolvers
                 // 4. Perform ! CreateDataPropertyOrThrow(obj, "promise", promiseCapability.[[Promise]]).
-                .property(js_string!("promise").into(), Attribute::all())
+                .property(js_str!("promise").into(), Attribute::all())
                 // 5. Perform ! CreateDataPropertyOrThrow(obj, "resolve", promiseCapability.[[Resolve]]).
-                .property(js_string!("resolve").into(), Attribute::all())
+                .property(js_str!("resolve").into(), Attribute::all())
                 // 6. Perform ! CreateDataPropertyOrThrow(obj, "reject", promiseCapability.[[Reject]]).
-                .property(js_string!("reject").into(), Attribute::all());
+                .property(js_str!("reject").into(), Attribute::all());
 
             with_resolvers
         };

core/engine/src/context/mod.rs

@@ -51,7 +51,7 @@ thread_local! {
 ///
 /// ```rust
 /// use boa_engine::{
-///     js_string,
+///     js_str,
 ///     object::ObjectInitializer,
 ///     property::{Attribute, PropertyDescriptor},
 ///     Context, Source,
@@ -73,10 +73,10 @@ thread_local! {
 ///
 /// // Create an object that can be used in eval calls.
 /// let arg = ObjectInitializer::new(&mut context)
-///     .property(js_string!("x"), 12, Attribute::READONLY)
+///     .property(js_str!("x"), 12, Attribute::READONLY)
 ///     .build();
 /// context
-///     .register_global_property(js_string!("arg"), arg, Attribute::all())
+///     .register_global_property(js_str!("arg"), arg, Attribute::all())
 ///     .expect("property shouldn't exist");
 ///
 /// let value = context.eval(Source::from_bytes("test(arg)")).unwrap();
@@ -211,7 +211,7 @@ impl Context {
     /// # Example
     /// ```
     /// use boa_engine::{
-    ///     js_string,
+    ///     js_str,
     ///     object::ObjectInitializer,
     ///     property::{Attribute, PropertyDescriptor},
     ///     Context,
@@ -221,19 +221,19 @@ impl Context {
     ///
     /// context
     ///     .register_global_property(
-    ///         js_string!("myPrimitiveProperty"),
+    ///         js_str!("myPrimitiveProperty"),
     ///         10,
     ///         Attribute::all(),
     ///     )
     ///     .expect("property shouldn't exist");
     ///
     /// let object = ObjectInitializer::new(&mut context)
-    ///     .property(js_string!("x"), 0, Attribute::all())
-    ///     .property(js_string!("y"), 1, Attribute::all())
+    ///     .property(js_str!("x"), 0, Attribute::all())
+    ///     .property(js_str!("y"), 1, Attribute::all())
     ///     .build();
     /// context
     ///     .register_global_property(
-    ///         js_string!("myObjectProperty"),
+    ///         js_str!("myObjectProperty"),
     ///         object,
     ///         Attribute::all(),
     ///     )

core/engine/src/error.rs

@@ -8,10 +8,10 @@ use crate::{
     object::JsObject,
     property::PropertyDescriptor,
     realm::Realm,
-    string::utf16,
     Context, JsString, JsValue,
 };
 use boa_gc::{custom_trace, Finalize, Trace};
+use boa_macros::js_str;
 use thiserror::Error;
 
 /// The error type returned by all operations related
@@ -30,11 +30,11 @@ use thiserror::Error;
 /// # Examples
 ///
 /// ```rust
-/// # use boa_engine::{JsError, JsNativeError, JsNativeErrorKind, JsValue, js_string};
-/// let cause = JsError::from_opaque(js_string!("error!").into());
+/// # use boa_engine::{JsError, JsNativeError, JsNativeErrorKind, JsValue, js_str};
+/// let cause = JsError::from_opaque(js_str!("error!").into());
 ///
 /// assert!(cause.as_opaque().is_some());
-/// assert_eq!(cause.as_opaque().unwrap(), &JsValue::from(js_string!("error!")));
+/// assert_eq!(cause.as_opaque().unwrap(), &JsValue::from(js_str!("error!")));
 ///
 /// let native_error: JsError = JsNativeError::typ()
 ///     .with_message("invalid type!")
@@ -270,7 +270,7 @@ impl JsError {
                     ErrorObject::Syntax => JsNativeErrorKind::Syntax,
                     ErrorObject::Uri => JsNativeErrorKind::Uri,
                     ErrorObject::Aggregate => {
-                        let errors = obj.get(utf16!("errors"), context).map_err(|e| {
+                        let errors = obj.get(js_str!("errors"), context).map_err(|e| {
                             TryNativeError::InaccessibleProperty {
                                 property: "errors",
                                 source: e,
@@ -878,7 +878,7 @@ impl JsNativeError {
     /// # Examples
     ///
     /// ```rust
-    /// # use boa_engine::{Context, JsError, JsNativeError, js_string};
+    /// # use boa_engine::{Context, JsError, JsNativeError, js_str};
     /// # use boa_engine::builtins::error::ErrorObject;
     /// let context = &mut Context::default();
     ///
@@ -887,8 +887,8 @@ impl JsNativeError {
     ///
     /// assert!(error_obj.is::<ErrorObject>());
     /// assert_eq!(
-    ///     error_obj.get(js_string!("message"), context).unwrap(),
-    ///     js_string!("error!").into()
+    ///     error_obj.get(js_str!("message"), context).unwrap(),
+    ///     js_str!("error!").into()
     /// )
     /// ```
     ///
@@ -941,14 +941,14 @@ impl JsNativeError {
             JsObject::from_proto_and_data_with_shared_shape(context.root_shape(), prototype, tag);
 
         o.create_non_enumerable_data_property_or_throw(
-            js_string!("message"),
+            js_str!("message"),
             js_string!(&**message),
             context,
         );
 
         if let Some(cause) = cause {
             o.create_non_enumerable_data_property_or_throw(
-                js_string!("cause"),
+                js_str!("cause"),
                 cause.to_opaque(context),
                 context,
             );
@@ -961,7 +961,7 @@ impl JsNativeError {
                 .collect::<Vec<_>>();
             let errors = Array::create_array_from_list(errors, context);
             o.define_property_or_throw(
-                js_string!("errors"),
+                js_str!("errors"),
                 PropertyDescriptor::builder()
                     .configurable(true)
                     .enumerable(false)

core/engine/src/lib.rs

@@ -77,7 +77,6 @@
 compile_error!("Boa requires a lock free `AtomicUsize` in order to work properly.");
 
 extern crate self as boa_engine;
-extern crate static_assertions as sa;
 
 pub use boa_ast as ast;
 pub use boa_gc as gc;
@@ -104,10 +103,11 @@ pub mod symbol;
 pub mod value;
 pub mod vm;
 
+pub(crate) mod tagged;
+
 mod host_defined;
 mod small_map;
 mod sys;
-mod tagged;
 
 #[cfg(test)]
 mod tests;
@@ -123,12 +123,12 @@ pub mod prelude {
         native_function::NativeFunction,
         object::{JsData, JsObject, NativeObject},
         script::Script,
-        string::JsString,
+        string::{JsStr, JsString},
         symbol::JsSymbol,
         value::JsValue,
     };
     pub use boa_gc::{Finalize, Trace};
-    pub use boa_macros::JsData;
+    pub use boa_macros::{js_str, JsData};
     pub use boa_parser::Source;
 }
 
@@ -138,6 +138,9 @@ use std::result::Result as StdResult;
 #[doc(inline)]
 pub use prelude::*;
 
+#[doc(inline)]
+pub use boa_parser::Source;
+
 /// The result of a Javascript expression is represented like this so it can succeed (`Ok`) or fail (`Err`)
 pub type JsResult<T> = StdResult<T, JsError>;
 

core/engine/src/module/source.rs

@@ -12,7 +12,7 @@ use boa_ast::{
 };
 use boa_gc::{Finalize, Gc, GcRefCell, Trace};
 use boa_interner::Interner;
-use boa_macros::utf16;
+use boa_macros::js_str;
 use indexmap::IndexSet;
 use rustc_hash::{FxHashMap, FxHashSet, FxHasher};
 
@@ -506,7 +506,7 @@ impl SourceTextModule {
             // c. For each element n of starNames, do
             for n in requested_module.get_exported_names(export_star_set, interner) {
                 // i. If SameValue(n, "default") is false, then
-                if &n != utf16!("default") {
+                if n != js_str!("default") {
                     // 1. If exportedNames does not contain n, then
                     //    a. Append n to exportedNames.
                     exported_names.insert(n);
@@ -583,7 +583,7 @@ impl SourceTextModule {
         }
 
         // 7. If SameValue(exportName, "default") is true, then
-        if &export_name.clone() == utf16!("default") {
+        if export_name == &js_str!("default") {
             // a. Assert: A default export was not explicitly defined by this module.
             // b. Return null.
             // c. NOTE: A default export cannot be provided by an export * from "mod" declaration.

core/engine/src/object/builtins/jsdate.rs

@@ -18,7 +18,7 @@ use time::{format_description::well_known::Rfc3339, OffsetDateTime};
 ///
 /// ```
 /// use boa_engine::{
-///     js_string, object::builtins::JsDate, Context, JsResult, JsValue,
+///     js_str, object::builtins::JsDate, Context, JsResult, JsValue,
 /// };
 ///
 /// fn main() -> JsResult<()> {
@@ -31,7 +31,7 @@ use time::{format_description::well_known::Rfc3339, OffsetDateTime};
 ///
 ///     assert_eq!(
 ///         date.to_date_string(context)?,
-///         JsValue::from(js_string!("Mon Dec 04 1995"))
+///         JsValue::from(js_str!("Mon Dec 04 1995"))
 ///     );
 ///
 ///     Ok(())

core/engine/src/object/builtins/jsmap.rs

@@ -4,12 +4,12 @@ use crate::{
     builtins::Map,
     error::JsNativeError,
     object::{JsFunction, JsMapIterator, JsObject, JsObjectType},
-    string::utf16,
     value::TryFromJs,
     Context, JsResult, JsValue,
 };
 
 use boa_gc::{Finalize, Trace};
+use boa_macros::js_str;
 use std::ops::Deref;
 
 /// `JsMap` provides a wrapper for Boa's implementation of the ECMAScript `Map` object.
@@ -20,7 +20,7 @@ use std::ops::Deref;
 /// ```
 /// # use boa_engine::{
 /// #  object::builtins::JsMap,
-/// #  Context, JsValue, JsResult, js_string
+/// #  Context, JsValue, JsResult, js_str
 /// # };
 /// # fn main() -> JsResult<()> {
 /// // Create default `Context`
@@ -30,8 +30,8 @@ use std::ops::Deref;
 /// let map = JsMap::new(context);
 ///
 /// // Set key-value pairs for the `JsMap`.
-/// map.set(js_string!("Key-1"), js_string!("Value-1"), context)?;
-/// map.set(js_string!("Key-2"), 10, context)?;
+/// map.set(js_str!("Key-1"), js_str!("Value-1"), context)?;
+/// map.set(js_str!("Key-2"), 10, context)?;
 ///
 /// assert_eq!(map.get_size(context)?, 2.into());
 /// # Ok(())
@@ -42,7 +42,7 @@ use std::ops::Deref;
 /// ```
 /// # use boa_engine::{
 /// #    object::builtins::{JsArray, JsMap},
-/// #    Context, JsValue, JsResult, js_string
+/// #    Context, JsValue, JsResult, js_str
 /// # };
 /// # fn main() -> JsResult<()> {
 /// // Create a default `Context`
@@ -53,8 +53,8 @@ use std::ops::Deref;
 ///
 /// // Create a `[key, value]` pair of JsValues
 /// let vec_one: Vec<JsValue> = vec![
-///     js_string!("first-key").into(),
-///     js_string!("first-value").into()
+///     js_str!("first-key").into(),
+///     js_str!("first-value").into()
 /// ];
 ///
 /// // We create an push our `[key, value]` pair onto our array as a `JsArray`
@@ -64,8 +64,8 @@ use std::ops::Deref;
 /// let js_iterable_map = JsMap::from_js_iterable(&js_array.into(), context)?;
 ///
 /// assert_eq!(
-///     js_iterable_map.get(js_string!("first-key"), context)?,
-///     js_string!("first-value").into()
+///     js_iterable_map.get(js_str!("first-key"), context)?,
+///     js_str!("first-value").into()
 /// );
 ///
 /// # Ok(())
@@ -102,7 +102,7 @@ impl JsMap {
     /// ```
     /// # use boa_engine::{
     /// #    object::builtins::{JsArray, JsMap},
-    /// #    Context, JsResult, JsValue, js_string
+    /// #    Context, JsResult, JsValue, js_str
     /// # };
     /// # fn main() -> JsResult<()> {
     /// # // Create a default `Context`
@@ -112,8 +112,8 @@ impl JsMap {
     ///
     /// // Create a `[key, value]` pair of JsValues and add it to the `JsArray` as a `JsArray`
     /// let vec_one: Vec<JsValue> = vec![
-    ///     js_string!("first-key").into(),
-    ///     js_string!("first-value").into()
+    ///     js_str!("first-key").into(),
+    ///     js_str!("first-value").into()
     /// ];
     /// js_array.push(JsArray::from_iter(vec_one, context), context)?;
     ///
@@ -129,7 +129,7 @@ impl JsMap {
 
         // Let adder be Get(map, "set") per spec. This action should not fail with default map.
         let adder = map
-            .get(utf16!("set"), context)
+            .get(js_str!("set"), context)
             .expect("creating a map with the default prototype must not fail");
 
         let _completion_record = add_entries_from_iterable(&map, iterable, &adder, context)?;
@@ -223,18 +223,18 @@ impl JsMap {
     /// ```
     /// # use boa_engine::{
     /// #    object::builtins::JsMap,
-    /// #    Context, JsValue, JsResult, js_string
+    /// #    Context, JsValue, JsResult, js_str
     /// # };
     /// # fn main() -> JsResult<()> {
     /// # let context = &mut Context::default();
     /// let js_map = JsMap::new(context);
     ///
-    /// js_map.set(js_string!("foo"), js_string!("bar"), context)?;
+    /// js_map.set(js_str!("foo"), js_str!("bar"), context)?;
     /// js_map.set(2, 4, context)?;
     ///
     /// assert_eq!(
-    ///     js_map.get(js_string!("foo"), context)?,
-    ///     js_string!("bar").into()
+    ///     js_map.get(js_str!("foo"), context)?,
+    ///     js_str!("bar").into()
     /// );
     /// assert_eq!(js_map.get(2, context)?, 4.into());
     /// # Ok(())
@@ -259,13 +259,13 @@ impl JsMap {
     /// ```
     /// # use boa_engine::{
     /// #    object::builtins::JsMap,
-    /// #    Context, JsValue, JsResult, js_string
+    /// #    Context, JsValue, JsResult, js_str
     /// # };
     /// # fn main() -> JsResult<()> {
     /// # let context = &mut Context::default();
     /// let js_map = JsMap::new(context);
     ///
-    /// js_map.set(js_string!("foo"), js_string!("bar"), context)?;
+    /// js_map.set(js_str!("foo"), js_str!("bar"), context)?;
     ///
     /// let map_size = js_map.get_size(context)?;
     ///
@@ -285,19 +285,19 @@ impl JsMap {
     /// ```
     /// # use boa_engine::{
     /// #    object::builtins::JsMap,
-    /// #    Context, JsValue, JsResult, js_string
+    /// #    Context, JsValue, JsResult, js_str
     /// # };
     /// # fn main() -> JsResult<()> {
     /// # let context = &mut Context::default();
     /// let js_map = JsMap::new(context);
-    /// js_map.set(js_string!("foo"), js_string!("bar"), context)?;
-    /// js_map.set(js_string!("hello"), js_string!("world"), context)?;
+    /// js_map.set(js_str!("foo"), js_str!("bar"), context)?;
+    /// js_map.set(js_str!("hello"), js_str!("world"), context)?;
     ///
-    /// js_map.delete(js_string!("foo"), context)?;
+    /// js_map.delete(js_str!("foo"), context)?;
     ///
     /// assert_eq!(js_map.get_size(context)?, 1.into());
     /// assert_eq!(
-    ///     js_map.get(js_string!("foo"), context)?,
+    ///     js_map.get(js_str!("foo"), context)?,
     ///     JsValue::undefined()
     /// );
     /// # Ok(())
@@ -317,16 +317,16 @@ impl JsMap {
     /// ```
     /// # use boa_engine::{
     /// #    object::builtins::JsMap,
-    /// #    Context, JsValue, JsResult, js_string
+    /// #    Context, JsValue, JsResult, js_str
     /// # };
     /// # fn main() -> JsResult<()> {
     /// # let context = &mut Context::default();
     /// let js_map = JsMap::new(context);
-    /// js_map.set(js_string!("foo"), js_string!("bar"), context)?;
+    /// js_map.set(js_str!("foo"), js_str!("bar"), context)?;
     ///
-    /// let retrieved_value = js_map.get(js_string!("foo"), context)?;
+    /// let retrieved_value = js_map.get(js_str!("foo"), context)?;
     ///
-    /// assert_eq!(retrieved_value, js_string!("bar").into());
+    /// assert_eq!(retrieved_value, js_str!("bar").into());
     /// # Ok(())
     /// # }
     /// ```
@@ -344,13 +344,13 @@ impl JsMap {
     /// ```
     /// # use boa_engine::{
     /// #    object::builtins::JsMap,
-    /// #    Context, JsValue, JsResult, js_string
+    /// #    Context, JsValue, JsResult, js_str
     /// # };
     /// # fn main() -> JsResult<()> {
     /// # let context = &mut Context::default();
     /// let js_map = JsMap::new(context);
-    /// js_map.set(js_string!("foo"), js_string!("bar"), context)?;
-    /// js_map.set(js_string!("hello"), js_string!("world"), context)?;
+    /// js_map.set(js_str!("foo"), js_str!("bar"), context)?;
+    /// js_map.set(js_str!("hello"), js_str!("world"), context)?;
     ///
     /// js_map.clear(context)?;
     ///
@@ -370,14 +370,14 @@ impl JsMap {
     /// ```
     /// # use boa_engine::{
     /// #    object::builtins::JsMap,
-    /// #    Context, JsValue, JsResult, js_string
+    /// #    Context, JsValue, JsResult, js_str
     /// # };
     /// # fn main() -> JsResult<()> {
     /// # let context = &mut Context::default();
     /// let js_map = JsMap::new(context);
-    /// js_map.set(js_string!("foo"), js_string!("bar"), context)?;
+    /// js_map.set(js_str!("foo"), js_str!("bar"), context)?;
     ///
-    /// let has_key = js_map.has(js_string!("foo"), context)?;
+    /// let has_key = js_map.has(js_str!("foo"), context)?;
     ///
     /// assert_eq!(has_key, true.into());
     /// # Ok(())

core/engine/src/object/builtins/jspromise.rs

@@ -25,7 +25,7 @@ use boa_gc::{Finalize, Gc, GcRefCell, Trace};
 /// ```
 /// # use boa_engine::{
 /// #     builtins::promise::PromiseState,
-/// #     js_string,
+/// #     js_str,
 /// #     object::{builtins::JsPromise, FunctionObjectBuilder},
 /// #     property::Attribute,
 /// #     Context, JsArgs, JsError, JsValue, NativeFunction,
@@ -35,14 +35,14 @@ use boa_gc::{Finalize, Gc, GcRefCell, Trace};
 /// let context = &mut Context::default();
 ///
 /// context.register_global_property(
-///     js_string!("finally"),
+///     js_str!("finally"),
 ///     false,
 ///     Attribute::all(),
 /// );
 ///
 /// let promise = JsPromise::new(
 ///     |resolvers, context| {
-///         let result = js_string!("hello world!").into();
+///         let result = js_str!("hello world!").into();
 ///         resolvers.resolve.call(
 ///             &JsValue::undefined(),
 ///             &[result],
@@ -75,7 +75,7 @@ use boa_gc::{Finalize, Gc, GcRefCell, Trace};
 ///     .finally(
 ///         NativeFunction::from_fn_ptr(|_, _, context| {
 ///             context.global_object().clone().set(
-///                 js_string!("finally"),
+///                 js_str!("finally"),
 ///                 JsValue::from(true),
 ///                 true,
 ///                 context,
@@ -90,14 +90,14 @@ use boa_gc::{Finalize, Gc, GcRefCell, Trace};
 ///
 /// assert_eq!(
 ///     promise.state(),
-///     PromiseState::Fulfilled(js_string!("hello world!").into())
+///     PromiseState::Fulfilled(js_str!("hello world!").into())
 /// );
 ///
 /// assert_eq!(
 ///     context
 ///         .global_object()
 ///         .clone()
-///         .get(js_string!("finally"), context)?,
+///         .get(js_str!("finally"), context)?,
 ///     JsValue::from(true)
 /// );
 ///

core/engine/src/object/builtins/jsproxy.rs

@@ -1,16 +1,14 @@
 //! A Rust API wrapper for the `Proxy` Builtin ECMAScript Object
-use boa_gc::{Finalize, Trace};
-
+use super::JsFunction;
 use crate::{
     builtins::Proxy,
+    js_str,
     native_function::{NativeFunction, NativeFunctionPointer},
     object::{FunctionObjectBuilder, JsObject, JsObjectType},
-    string::utf16,
     value::TryFromJs,
     Context, JsNativeError, JsResult, JsValue,
 };
-
-use super::JsFunction;
+use boa_gc::{Finalize, Trace};
 
 /// `JsProxy` provides a wrapper for Boa's implementation of the ECMAScript `Proxy` object
 ///
@@ -405,7 +403,7 @@ impl JsProxyBuilder {
                 .length(3)
                 .build();
             handler
-                .create_data_property_or_throw(utf16!("apply"), f, context)
+                .create_data_property_or_throw(js_str!("apply"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(construct) = self.construct {
@@ -414,7 +412,7 @@ impl JsProxyBuilder {
                     .length(3)
                     .build();
             handler
-                .create_data_property_or_throw(utf16!("construct"), f, context)
+                .create_data_property_or_throw(js_str!("construct"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(define_property) = self.define_property {
@@ -425,7 +423,7 @@ impl JsProxyBuilder {
             .length(3)
             .build();
             handler
-                .create_data_property_or_throw(utf16!("defineProperty"), f, context)
+                .create_data_property_or_throw(js_str!("defineProperty"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(delete_property) = self.delete_property {
@@ -436,7 +434,7 @@ impl JsProxyBuilder {
             .length(2)
             .build();
             handler
-                .create_data_property_or_throw(utf16!("deleteProperty"), f, context)
+                .create_data_property_or_throw(js_str!("deleteProperty"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(get) = self.get {
@@ -444,7 +442,7 @@ impl JsProxyBuilder {
                 .length(3)
                 .build();
             handler
-                .create_data_property_or_throw(utf16!("get"), f, context)
+                .create_data_property_or_throw(js_str!("get"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(get_own_property_descriptor) = self.get_own_property_descriptor {
@@ -455,7 +453,7 @@ impl JsProxyBuilder {
             .length(2)
             .build();
             handler
-                .create_data_property_or_throw(utf16!("getOwnPropertyDescriptor"), f, context)
+                .create_data_property_or_throw(js_str!("getOwnPropertyDescriptor"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(get_prototype_of) = self.get_prototype_of {
@@ -466,7 +464,7 @@ impl JsProxyBuilder {
             .length(1)
             .build();
             handler
-                .create_data_property_or_throw(utf16!("getPrototypeOf"), f, context)
+                .create_data_property_or_throw(js_str!("getPrototypeOf"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(has) = self.has {
@@ -474,7 +472,7 @@ impl JsProxyBuilder {
                 .length(2)
                 .build();
             handler
-                .create_data_property_or_throw(utf16!("has"), f, context)
+                .create_data_property_or_throw(js_str!("has"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(is_extensible) = self.is_extensible {
@@ -485,7 +483,7 @@ impl JsProxyBuilder {
             .length(1)
             .build();
             handler
-                .create_data_property_or_throw(utf16!("isExtensible"), f, context)
+                .create_data_property_or_throw(js_str!("isExtensible"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(own_keys) = self.own_keys {
@@ -494,7 +492,7 @@ impl JsProxyBuilder {
                     .length(1)
                     .build();
             handler
-                .create_data_property_or_throw(utf16!("ownKeys"), f, context)
+                .create_data_property_or_throw(js_str!("ownKeys"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(prevent_extensions) = self.prevent_extensions {
@@ -505,7 +503,7 @@ impl JsProxyBuilder {
             .length(1)
             .build();
             handler
-                .create_data_property_or_throw(utf16!("preventExtensions"), f, context)
+                .create_data_property_or_throw(js_str!("preventExtensions"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(set) = self.set {
@@ -513,7 +511,7 @@ impl JsProxyBuilder {
                 .length(4)
                 .build();
             handler
-                .create_data_property_or_throw(utf16!("set"), f, context)
+                .create_data_property_or_throw(js_str!("set"), f, context)
                 .expect("new object should be writable");
         }
         if let Some(set_prototype_of) = self.set_prototype_of {
@@ -524,7 +522,7 @@ impl JsProxyBuilder {
             .length(2)
             .build();
             handler
-                .create_data_property_or_throw(utf16!("setPrototypeOf"), f, context)
+                .create_data_property_or_throw(js_str!("setPrototypeOf"), f, context)
                 .expect("new object should be writable");
         }
 

core/engine/src/object/internal_methods/string.rs

@@ -1,5 +1,4 @@
 use crate::{
-    js_string,
     object::{JsData, JsObject},
     property::{PropertyDescriptor, PropertyKey},
     Context, JsResult, JsString,
@@ -158,7 +157,7 @@ fn string_get_own_property(obj: &JsObject, key: &PropertyKey) -> Option<Property
     // 10. Let len be the length of str.
     // 11. If ℝ(index) < 0 or len ≤ ℝ(index), return undefined.
     // 12. Let resultStr be the String value of length 1, containing one code unit from str, specifically the code unit at index ℝ(index).
-    let result_str = js_string!(string.get(pos..=pos)?);
+    let result_str = string.get(pos..=pos)?;
 
     // 13. Return the PropertyDescriptor { [[Value]]: resultStr, [[Writable]]: false, [[Enumerable]]: true, [[Configurable]]: false }.
     let desc = PropertyDescriptor::builder()

core/engine/src/object/jsobject.rs

@@ -17,11 +17,11 @@ use crate::{
     error::JsNativeError,
     js_string,
     property::{PropertyDescriptor, PropertyKey},
-    string::utf16,
     value::PreferredType,
     Context, JsResult, JsString, JsValue,
 };
 use boa_gc::{self, Finalize, Gc, GcBox, GcRefCell, Trace};
+use boa_macros::js_str;
 use std::{
     cell::RefCell,
     collections::HashMap,
@@ -337,9 +337,9 @@ impl JsObject {
         // 4. Else,
         //    a. Let methodNames be « "valueOf", "toString" ».
         let method_names = if hint == PreferredType::String {
-            [utf16!("toString"), utf16!("valueOf")]
+            [js_str!("toString"), js_str!("valueOf")]
         } else {
-            [utf16!("valueOf"), utf16!("toString")]
+            [js_str!("valueOf"), js_str!("toString")]
         };
 
         // 5. For each name in methodNames in List order, do
@@ -379,41 +379,41 @@ impl JsObject {
 
         // 3. Let hasEnumerable be ? HasProperty(Obj, "enumerable").
         // 4. If hasEnumerable is true, then ...
-        if self.has_property(utf16!("enumerable"), context)? {
+        if self.has_property(js_str!("enumerable"), context)? {
             // a. Let enumerable be ! ToBoolean(? Get(Obj, "enumerable")).
             // b. Set desc.[[Enumerable]] to enumerable.
-            desc = desc.enumerable(self.get(utf16!("enumerable"), context)?.to_boolean());
+            desc = desc.enumerable(self.get(js_str!("enumerable"), context)?.to_boolean());
         }
 
         // 5. Let hasConfigurable be ? HasProperty(Obj, "configurable").
         // 6. If hasConfigurable is true, then ...
-        if self.has_property(utf16!("configurable"), context)? {
+        if self.has_property(js_str!("configurable"), context)? {
             // a. Let configurable be ! ToBoolean(? Get(Obj, "configurable")).
             // b. Set desc.[[Configurable]] to configurable.
-            desc = desc.configurable(self.get(utf16!("configurable"), context)?.to_boolean());
+            desc = desc.configurable(self.get(js_str!("configurable"), context)?.to_boolean());
         }
 
         // 7. Let hasValue be ? HasProperty(Obj, "value").
         // 8. If hasValue is true, then ...
-        if self.has_property(utf16!("value"), context)? {
+        if self.has_property(js_str!("value"), context)? {
             // a. Let value be ? Get(Obj, "value").
             // b. Set desc.[[Value]] to value.
-            desc = desc.value(self.get(utf16!("value"), context)?);
+            desc = desc.value(self.get(js_str!("value"), context)?);
         }
 
         // 9. Let hasWritable be ? HasProperty(Obj, ).
         // 10. If hasWritable is true, then ...
-        if self.has_property(utf16!("writable"), context)? {
+        if self.has_property(js_str!("writable"), context)? {
             // a. Let writable be ! ToBoolean(? Get(Obj, "writable")).
             // b. Set desc.[[Writable]] to writable.
-            desc = desc.writable(self.get(utf16!("writable"), context)?.to_boolean());
+            desc = desc.writable(self.get(js_str!("writable"), context)?.to_boolean());
         }
 
         // 11. Let hasGet be ? HasProperty(Obj, "get").
         // 12. If hasGet is true, then
-        let get = if self.has_property(utf16!("get"), context)? {
+        let get = if self.has_property(js_str!("get"), context)? {
             // a. Let getter be ? Get(Obj, "get").
-            let getter = self.get(utf16!("get"), context)?;
+            let getter = self.get(js_str!("get"), context)?;
             // b. If IsCallable(getter) is false and getter is not undefined, throw a TypeError exception.
             // todo: extract IsCallable to be callable from Value
             if !getter.is_undefined() && getter.as_object().map_or(true, |o| !o.is_callable()) {
@@ -429,9 +429,9 @@ impl JsObject {
 
         // 13. Let hasSet be ? HasProperty(Obj, "set").
         // 14. If hasSet is true, then
-        let set = if self.has_property(utf16!("set"), context)? {
+        let set = if self.has_property(js_str!("set"), context)? {
             // 14.a. Let setter be ? Get(Obj, "set").
-            let setter = self.get(utf16!("set"), context)?;
+            let setter = self.get(js_str!("set"), context)?;
             // 14.b. If IsCallable(setter) is false and setter is not undefined, throw a TypeError exception.
             // todo: extract IsCallable to be callable from Value
             if !setter.is_undefined() && setter.as_object().map_or(true, |o| !o.is_callable()) {
@@ -940,7 +940,7 @@ impl<T: NativeObject + ?Sized> Debug for JsObject<T> {
             if self.is_callable() {
                 let name_prop = obj
                     .properties()
-                    .get(&PropertyKey::String(JsString::from("name")));
+                    .get(&PropertyKey::String(js_string!("name")));
                 let name = match name_prop {
                     None => JsString::default(),
                     Some(prop) => prop

core/engine/src/object/mod.rs

@@ -2,6 +2,7 @@
 //!
 //! For the builtin object wrappers, please see [`object::builtins`][builtins] for implementors.
 
+use boa_macros::js_str;
 pub use jsobject::{RecursionLimiter, Ref, RefMut};
 pub use operations::IntegrityLevel;
 pub use property_map::*;
@@ -22,8 +23,8 @@ use crate::{
     native_function::{NativeFunction, NativeFunctionObject},
     property::{Attribute, PropertyDescriptor, PropertyKey},
     realm::Realm,
-    string::{common::StaticJsStrings, utf16},
-    Context, JsString, JsSymbol, JsValue,
+    string::common::StaticJsStrings,
+    Context, JsStr, JsString, JsSymbol, JsValue,
 };
 
 use boa_gc::{Finalize, Trace};
@@ -52,10 +53,10 @@ pub use jsobject::*;
 pub(crate) trait JsObjectType: Into<JsValue> + Into<JsObject> {}
 
 /// Const `constructor`, usually set on prototypes as a key to point to their respective constructor object.
-pub const CONSTRUCTOR: &[u16] = utf16!("constructor");
+pub const CONSTRUCTOR: JsStr<'_> = js_str!("constructor");
 
 /// Const `prototype`, usually set on constructors as a key to point to their respective prototype object.
-pub const PROTOTYPE: &[u16] = utf16!("prototype");
+pub const PROTOTYPE: JsStr<'_> = js_str!("prototype");
 
 /// Common field names.
 
@@ -1017,7 +1018,7 @@ impl<'ctx> ConstructorBuilder<'ctx> {
             };
 
             constructor.insert(StaticJsStrings::LENGTH, length);
-            constructor.insert(utf16!("name"), name);
+            constructor.insert(js_str!("name"), name);
 
             if let Some(proto) = self.custom_prototype.take() {
                 constructor.set_prototype(proto);