Refactor iterator APIs to be on parity with the latest spec (#3962)

* The Great Refactoring Of Iterators

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

Co-authored-by: raskad <32105367+raskad@users.noreply.github.com>

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

Co-authored-by: raskad <32105367+raskad@users.noreply.github.com>

---------

Co-authored-by: raskad <32105367+raskad@users.noreply.github.com>

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

@@ -15,10 +15,7 @@ use boa_profiler::Profiler;
 use thin_vec::ThinVec;
 
 use crate::{
-    builtins::{
-        iterable::{if_abrupt_close_iterator, IteratorHint},
-        BuiltInObject, Number,
-    },
+    builtins::{iterable::if_abrupt_close_iterator, BuiltInObject, Number},
     context::intrinsics::{Intrinsics, StandardConstructor, StandardConstructors},
     error::JsNativeError,
     js_string,
@@ -610,44 +607,41 @@ impl Array {
             _ => Self::array_create(0, None, context)?,
         };
 
-        // c. Let iteratorRecord be ? GetIterator(items, sync, usingIterator).
-        let mut iterator_record =
-            items.get_iterator(context, Some(IteratorHint::Sync), Some(using_iterator))?;
+        // c. Let iteratorRecord be ? GetIteratorFromMethod(items, usingIterator).
+        let mut iterator_record = items.get_iterator_from_method(&using_iterator, context)?;
 
         // d. Let k be 0.
         // e. Repeat,
         //     i. If k ≥ 2^53 - 1 (MAX_SAFE_INTEGER), then
         //     ...
-        //     x. Set k to k + 1.
+        //     ix. Set k to k + 1.
         for k in 0..9_007_199_254_740_991_u64 {
-            // iii. Let next be ? IteratorStep(iteratorRecord).
-            if iterator_record.step(context)? {
+            // iii. Let next be ? IteratorStepValue(iteratorRecord).
+            let Some(next) = iterator_record.step_value(context)? else {
+                // iv. If next is done, then
                 //     1. Perform ? Set(A, "length", 𝔽(k), true).
                 a.set(StaticJsStrings::LENGTH, k, true, context)?;
                 //     2. Return A.
                 return Ok(a.into());
-            }
-
-            // iv. If next is false, then
-            // v. Let nextValue be ? IteratorValue(next).
-            let next_value = iterator_record.value(context)?;
+            };
 
-            // vi. If mapping is true, then
+            // v. If mapping is true, then
             let mapped_value = if let Some(mapfn) = mapping {
-                // 1. Let mappedValue be Call(mapfn, thisArg, « nextValue, 𝔽(k) »).
-                let mapped_value = mapfn.call(this_arg, &[next_value, k.into()], context);
+                // 1. Let mappedValue be Completion(Call(mapper, thisArg, « next, 𝔽(k) »)).
+                let mapped_value = mapfn.call(this_arg, &[next, k.into()], context);
 
                 // 2. IfAbruptCloseIterator(mappedValue, iteratorRecord).
                 if_abrupt_close_iterator!(mapped_value, iterator_record, context)
             } else {
-                // vii. Else, let mappedValue be nextValue.
-                next_value
+                // vi. Else,
+                //     1. Let mappedValue be next.
+                next
             };
 
-            // viii. Let defineStatus be CreateDataPropertyOrThrow(A, Pk, mappedValue).
+            // vii. Let defineStatus be Completion(CreateDataPropertyOrThrow(A, Pk, mappedValue)).
             let define_status = a.create_data_property_or_throw(k, mapped_value, context);
 
-            // ix. IfAbruptCloseIterator(defineStatus, iteratorRecord).
+            // viii. IfAbruptCloseIterator(defineStatus, iteratorRecord).
             if_abrupt_close_iterator!(define_status, iterator_record, context);
         }
 

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

@@ -9,7 +9,7 @@
 
 use crate::{
     builtins::{
-        iterable::iterable_to_list, Array, BuiltInBuilder, BuiltInConstructor, BuiltInObject,
+        iterable::IteratorHint, Array, BuiltInBuilder, BuiltInConstructor, BuiltInObject,
         IntrinsicObject,
     },
     context::intrinsics::{Intrinsics, StandardConstructor, StandardConstructors},
@@ -56,7 +56,11 @@ impl BuiltInConstructor for AggregateError {
     const STANDARD_CONSTRUCTOR: fn(&StandardConstructors) -> &StandardConstructor =
         StandardConstructors::aggregate_error;
 
-    /// Create a new aggregate error object.
+    /// [`AggregateError ( errors, message [ , options ] )`][spec]
+    ///
+    /// Creates a new aggregate error object.
+    ///
+    /// [spec]: AggregateError ( errors, message [ , options ] )
     fn constructor(
         new_target: &JsValue,
         args: &[JsValue],
@@ -102,9 +106,12 @@ impl BuiltInConstructor for AggregateError {
         // 4. Perform ? InstallErrorCause(O, options).
         Error::install_error_cause(&o, args.get_or_undefined(2), context)?;
 
-        // 5. Let errorsList be ? IterableToList(errors).
+        // 5. Let errorsList be ? IteratorToList(? GetIterator(errors, sync)).
         let errors = args.get_or_undefined(0);
-        let errors_list = iterable_to_list(context, errors, None)?;
+        let errors_list = errors
+            .get_iterator(IteratorHint::Sync, context)?
+            .into_list(context)?;
+
         // 6. Perform ! DefinePropertyOrThrow(O, "errors",
         //    PropertyDescriptor {
         //      [[Configurable]]: true,

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

@@ -9,6 +9,7 @@ use icu_provider::DataLocale;
 
 use crate::{
     builtins::{
+        iterable::IteratorHint,
         options::{get_option, get_options_object},
         Array, BuiltInBuilder, BuiltInConstructor, BuiltInObject, IntrinsicObject, OrdinaryObject,
     },
@@ -486,23 +487,20 @@ fn string_list_from_iterable(iterable: &JsValue, context: &mut Context) -> JsRes
         return Ok(Vec::new());
     }
 
-    // 2. Let iteratorRecord be ? GetIterator(iterable).
-    let mut iterator = iterable.get_iterator(context, None, None)?;
+    // 2. Let iteratorRecord be ? GetIterator(iterable, sync).
+    let mut iterator = iterable.get_iterator(IteratorHint::Sync, context)?;
 
     // 3. Let list be a new empty List.
     let mut list = Vec::new();
 
     // 4. Let next be true.
     // 5. Repeat, while next is not false,
-    //     a. Set next to ? IteratorStep(iteratorRecord).
-    //     b. If next is not false, then
-    while !iterator.step(context)? {
-        let item = iterator.value(context)?;
-        //    i. Let nextValue be ? IteratorValue(next).
-        //    ii. If Type(nextValue) is not String, then
-        let Some(s) = item.as_string().cloned() else {
-            //    1. Let error be ThrowCompletion(a newly created TypeError object).
-            //    2. Return ? IteratorClose(iteratorRecord, error).
+    //     a. Let next be ? IteratorStepValue(iteratorRecord).
+    while let Some(next) = iterator.step_value(context)? {
+        // c. If next is not a String, then
+        let Some(s) = next.as_string().cloned() else {
+            // i. Let error be ThrowCompletion(a newly created TypeError object).
+            // ii. Return ? IteratorClose(iteratorRecord, error).
             return Err(iterator
                 .close(
                     Err(JsNativeError::typ()
@@ -510,13 +508,14 @@ fn string_list_from_iterable(iterable: &JsValue, context: &mut Context) -> JsRes
                         .into()),
                     context,
                 )
-                .expect_err("Should return the provided error"));
+                .expect_err("`close` should return the provided error"));
         };
 
-        //    iii. Append nextValue to the end of the List list.
+        // d. Append next to list.
         list.push(s);
     }
 
-    // 6. Return list.
+    //     b. If next is done, then
+    //         i. Return list.
     Ok(list)
 }

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

@@ -98,7 +98,7 @@ impl AsyncFromSyncIterator {
         // 1. Let O be the this value.
         // 2. Assert: O is an Object that has a [[SyncIteratorRecord]] internal slot.
         // 4. Let syncIteratorRecord be O.[[SyncIteratorRecord]].
-        let sync_iterator_record = this
+        let mut sync_iterator_record = this
             .as_object()
             .and_then(JsObject::downcast_ref::<Self>)
             .expect("async from sync iterator prototype must be object")
@@ -116,15 +116,7 @@ impl AsyncFromSyncIterator {
         //     a. Let result be Completion(IteratorNext(syncIteratorRecord, value)).
         // 6. Else,
         //     a. Let result be Completion(IteratorNext(syncIteratorRecord)).
-        let iterator = sync_iterator_record.iterator().clone();
-        let next = sync_iterator_record.next_method();
-        let result = next
-            .call(
-                &iterator.into(),
-                args.first().map_or(&[], std::slice::from_ref),
-                context,
-            )
-            .and_then(IteratorResult::from_value);
+        let result = sync_iterator_record.next(args.first(), context);
 
         // 7. IfAbruptRejectPromise(result, promiseCapability).
         let result = if_abrupt_reject_promise!(result, promise_capability, context);

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

@@ -225,7 +225,31 @@ pub enum IteratorHint {
 }
 
 impl JsValue {
-    /// `GetIterator ( obj [ , hint [ , method ] ] )`
+    /// `GetIteratorFromMethod ( obj, method )`
+    ///
+    /// More information:
+    ///  - [ECMA reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-getiteratorfrommethod
+    pub fn get_iterator_from_method(
+        &self,
+        method: &JsObject,
+        context: &mut Context,
+    ) -> JsResult<IteratorRecord> {
+        // 1. Let iterator be ? Call(method, obj).
+        let iterator = method.call(self, &[], context)?;
+        // 2. If iterator is not an Object, throw a TypeError exception.
+        let iterator_obj = iterator.as_object().ok_or_else(|| {
+            JsNativeError::typ().with_message("returned iterator is not an object")
+        })?;
+        // 3. Let nextMethod be ? Get(iterator, "next").
+        let next_method = iterator_obj.get(js_str!("next"), context)?;
+        // 4. Let iteratorRecord be the Iterator Record { [[Iterator]]: iterator, [[NextMethod]]: nextMethod, [[Done]]: false }.
+        // 5. Return iteratorRecord.
+        Ok(IteratorRecord::new(iterator_obj.clone(), next_method))
+    }
+
+    /// `GetIterator ( obj, kind )`
     ///
     /// More information:
     ///  - [ECMA reference][spec]
@@ -233,60 +257,51 @@ impl JsValue {
     /// [spec]: https://tc39.es/ecma262/#sec-getiterator
     pub fn get_iterator(
         &self,
+        hint: IteratorHint,
         context: &mut Context,
-        hint: Option<IteratorHint>,
-        method: Option<JsObject>,
     ) -> JsResult<IteratorRecord> {
-        // 1. If hint is not present, set hint to sync.
-        let hint = hint.unwrap_or(IteratorHint::Sync);
-
-        // 2. If method is not present, then
-        let method = if method.is_some() {
-            method
-        } else {
-            // a. If hint is async, then
-            if hint == IteratorHint::Async {
-                // i. Set method to ? GetMethod(obj, @@asyncIterator).
-                if let Some(method) = self.get_method(JsSymbol::async_iterator(), context)? {
-                    Some(method)
-                } else {
-                    // ii. If method is undefined, then
-                    // 1. Let syncMethod be ? GetMethod(obj, @@iterator).
-                    let sync_method = self.get_method(JsSymbol::iterator(), context)?;
-
-                    // 2. Let syncIteratorRecord be ? GetIterator(obj, sync, syncMethod).
-                    let sync_iterator_record =
-                        self.get_iterator(context, Some(IteratorHint::Sync), sync_method)?;
-
-                    // 3. Return ! CreateAsyncFromSyncIterator(syncIteratorRecord).
-                    return Ok(AsyncFromSyncIterator::create(sync_iterator_record, context));
-                }
-            } else {
-                // b. Otherwise, set method to ? GetMethod(obj, @@iterator).
+        let method = match hint {
+            // 1. If kind is async, then
+            IteratorHint::Async => {
+                // a. Let method be ? GetMethod(obj, %Symbol.asyncIterator%).
+                let Some(method) = self.get_method(JsSymbol::async_iterator(), context)? else {
+                    // b. If method is undefined, then
+                    //     i. Let syncMethod be ? GetMethod(obj, %Symbol.iterator%).
+                    let sync_method =
                         self.get_method(JsSymbol::iterator(), context)?
-            }
-        }
                             .ok_or_else(|| {
+                                // ii. If syncMethod is undefined, throw a TypeError exception.
                                 JsNativeError::typ().with_message(format!(
                                     "value with type `{}` is not iterable",
                                     self.type_of()
                                 ))
                             })?;
+                    // iii. Let syncIteratorRecord be ? GetIteratorFromMethod(obj, syncMethod).
+                    let sync_iterator_record =
+                        self.get_iterator_from_method(&sync_method, context)?;
+                    // iv. Return CreateAsyncFromSyncIterator(syncIteratorRecord).
+                    return Ok(AsyncFromSyncIterator::create(sync_iterator_record, context));
+                };
 
-        // 3. Let iterator be ? Call(method, obj).
-        let iterator = method.call(self, &[], context)?;
+                Some(method)
+            }
+            // 2. Else,
+            IteratorHint::Sync => {
+                // a. Let method be ? GetMethod(obj, %Symbol.iterator%).
+                self.get_method(JsSymbol::iterator(), context)?
+            }
+        };
 
-        // 4. If Type(iterator) is not Object, throw a TypeError exception.
-        let iterator_obj = iterator.as_object().ok_or_else(|| {
-            JsNativeError::typ().with_message("returned iterator is not an object")
+        let method = method.ok_or_else(|| {
+            // 3. If method is undefined, throw a TypeError exception.
+            JsNativeError::typ().with_message(format!(
+                "value with type `{}` is not iterable",
+                self.type_of()
+            ))
         })?;
 
-        // 5. Let nextMethod be ? GetV(iterator, "next").
-        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.
-        Ok(IteratorRecord::new(iterator_obj.clone(), next_method))
+        // 4. Return ? GetIteratorFromMethod(obj, method).
+        self.get_iterator_from_method(&method, context)
     }
 }
 
@@ -461,28 +476,35 @@ impl IteratorRecord {
     ///  - [ECMA reference][spec]
     ///
     /// [spec]: https://tc39.es/ecma262/#sec-iteratornext
-    pub(crate) fn step_with(
+    pub(crate) fn next(
         &mut self,
         value: Option<&JsValue>,
         context: &mut Context,
-    ) -> JsResult<bool> {
+    ) -> JsResult<IteratorResult> {
         let _timer = Profiler::global().start_event("IteratorRecord::step_with", "iterator");
 
-        self.set_done_on_err(|iter| {
         // 1. If value is not present, then
-            //     a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
+        //     a. Let result be Completion(Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]])).
         // 2. Else,
-            //     a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]], « value »).
-            let result = iter.next_method.call(
+        //     a. Let result be Completion(Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]], « value »)).
+        // 3. If result is a throw completion, then
+        //     a. Set iteratorRecord.[[Done]] to true.
+        //     b. Return ? result.
+        // 4. Set result to ! result.
+        // 5. If result is not an Object, then
+        //     a. Set iteratorRecord.[[Done]] to true.
+        //     b. Throw a TypeError exception.
+        // 6. Return result.
+        // NOTE: In this case, `set_done_on_err` does all the heavylifting for us, which
+        // simplifies the instructions below.
+        self.set_done_on_err(|iter| {
+            iter.next_method
+                .call(
                     &iter.iterator.clone().into(),
                     value.map_or(&[], std::slice::from_ref),
                     context,
-            )?;
-
-            iter.update_result(result, context)?;
-
-            // 4. Return result.
-            Ok(iter.done)
+                )
+                .and_then(IteratorResult::from_value)
         })
     }
 
@@ -497,7 +519,49 @@ impl IteratorRecord {
     ///
     /// [spec]: https://tc39.es/ecma262/#sec-iteratorstep
     pub(crate) fn step(&mut self, context: &mut Context) -> JsResult<bool> {
-        self.step_with(None, context)
+        self.set_done_on_err(|iter| {
+            // 1. Let result be ? IteratorNext(iteratorRecord).
+            let result = iter.next(None, context)?;
+
+            // 2. Let done be Completion(IteratorComplete(result)).
+            // 3. If done is a throw completion, then
+            //     a. Set iteratorRecord.[[Done]] to true.
+            //     b. Return ? done.
+            // 4. Set done to ! done.
+            // 5. If done is true, then
+            //     a. Set iteratorRecord.[[Done]] to true.
+            //     b. Return done.
+            iter.done = result.complete(context)?;
+
+            iter.last_result = result;
+
+            // 6. Return result.
+            Ok(iter.done)
+        })
+    }
+
+    /// `IteratorStepValue ( iteratorRecord )`
+    ///
+    /// Updates the `IteratorRecord` and returns `Some(value)` if the next result record returned
+    /// `done: true`, otherwise returns `None`.
+    ///
+    /// More information:
+    ///  - [ECMA reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-iteratorstepvalue
+    pub(crate) fn step_value(&mut self, context: &mut Context) -> JsResult<Option<JsValue>> {
+        // 1. Let result be ? IteratorStep(iteratorRecord).
+        if self.step(context)? {
+            // 2. If result is done, then
+            //     a. Return done.
+            Ok(None)
+        } else {
+            // 3. Let value be Completion(IteratorValue(result)).
+            // 4. If value is a throw completion, then
+            //     a. Set iteratorRecord.[[Done]] to true.
+            // 5. Return ? value.
+            self.value(context).map(Some)
+        }
     }
 
     /// `IteratorClose ( iteratorRecord, completion )`
@@ -565,40 +629,28 @@ impl IteratorRecord {
                 .into())
         }
     }
-}
 
-/// `IterableToList ( items [ , method ] )`
+    /// `IteratorToList ( iteratorRecord )`
     ///
     /// More information:
     ///  - [ECMA reference][spec]
     ///
-///  [spec]: https://tc39.es/ecma262/#sec-iterabletolist
-pub(crate) fn iterable_to_list(
-    context: &mut Context,
-    items: &JsValue,
-    method: Option<JsObject>,
-) -> JsResult<Vec<JsValue>> {
-    let _timer = Profiler::global().start_event("iterable_to_list", "iterator");
-
-    // 1. If method is present, then
-    // a. Let iteratorRecord be ? GetIterator(items, sync, method).
-    // 2. Else,
-    // a. Let iteratorRecord be ? GetIterator(items, sync).
-    let mut iterator_record = items.get_iterator(context, Some(IteratorHint::Sync), method)?;
+    ///  [spec]: https://tc39.es/ecma262/#sec-iteratortolist
+    pub(crate) fn into_list(mut self, context: &mut Context) -> JsResult<Vec<JsValue>> {
+        let _timer = Profiler::global().start_event("IteratorRecord::to_list", "iterator");
 
-    // 3. Let values be a new empty List.
+        // 1. Let values be a new empty List.
         let mut values = Vec::new();
 
-    // 4. Let next be true.
-    // 5. Repeat, while next is not false,
-    //     a. Set next to ? IteratorStep(iteratorRecord).
-    //     b. If next is not false, then
-    //         i. Let nextValue be ? IteratorValue(next).
-    //         ii. Append nextValue to the end of the List values.
-    while !iterator_record.step(context)? {
-        values.push(iterator_record.value(context)?);
+        // 2. Repeat,
+        //     a. Let next be ? IteratorStepValue(iteratorRecord).
+        while let Some(value) = self.step_value(context)? {
+            // c. Append next to values.
+            values.push(value);
         }
 
-    // 6. Return values.
+        //     b. If next is done, then
+        //         i. Return values.
         Ok(values)
     }
+}

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

@@ -11,11 +11,11 @@
 //! [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map
 
 use crate::{
-    builtins::BuiltInObject,
+    builtins::{iterable::IteratorHint, BuiltInObject},
     context::intrinsics::{Intrinsics, StandardConstructor, StandardConstructors},
     error::JsNativeError,
     js_string,
-    object::{internal_methods::get_prototype_from_constructor, JsObject},
+    object::{internal_methods::get_prototype_from_constructor, JsFunction, JsObject},
     property::{Attribute, PropertyNameKind},
     realm::Realm,
     string::StaticJsStrings,
@@ -26,7 +26,9 @@ use boa_macros::js_str;
 use boa_profiler::Profiler;
 use num_traits::Zero;
 
-use super::{BuiltInBuilder, BuiltInConstructor, IntrinsicObject};
+use super::{
+    iterable::if_abrupt_close_iterator, BuiltInBuilder, BuiltInConstructor, IntrinsicObject,
+};
 
 mod map_iterator;
 pub(crate) use map_iterator::MapIterator;
@@ -149,9 +151,16 @@ impl BuiltInConstructor for Map {
         };
 
         // 5. Let adder be ? Get(map, "set").
-        let adder = map.get(js_str!("set"), context)?;
+        // 6. If IsCallable(adder) is false, throw a TypeError exception.
+        let adder = map
+            .get(js_str!("set"), context)?
+            .as_function()
+            .ok_or_else(|| {
+                JsNativeError::typ()
+                    .with_message("Map: property `set` on new `Map` must be callable")
+            })?;
 
-        // 6. Return ? AddEntriesFromIterable(map, iterable, adder).
+        // 7. Return ? AddEntriesFromIterable(map, iterable, adder).
         add_entries_from_iterable(&map, iterable, &adder, context)
     }
 }
@@ -547,8 +556,8 @@ impl Map {
         let mut groups: IndexMap<JsValue, Vec<JsValue>, BuildHasherDefault<FxHasher>> =
             IndexMap::default();
 
-        // 4. Let iteratorRecord be ? GetIterator(items).
-        let mut iterator = items.get_iterator(context, None, None)?;
+        // 4. Let iteratorRecord be ? GetIterator(items, sync).
+        let mut iterator = items.get_iterator(IteratorHint::Sync, context)?;
 
         // 5. Let k be 0.
         let mut k = 0u64;
@@ -566,17 +575,15 @@ impl Map {
                 return iterator.close(Err(error), context);
             }
 
-            // b. Let next be ? IteratorStep(iteratorRecord).
-            let done = iterator.step(context)?;
-
+            // b. Let next be ? IteratorStepValue(iteratorRecord).
+            let Some(next) = iterator.step_value(context)? else {
                 // c. If next is false, then
-            if done {
                 // i. Return groups.
                 break;
-            }
+            };
 
-            // d. Let value be ? IteratorValue(next).
-            let value = iterator.value(context)?;
+            // d. Let value be next.
+            let value = next;
 
             // e. Let key be Completion(Call(callbackfn, undefined, « value, 𝔽(k) »)).
             let key = callback.call(&JsValue::undefined(), &[value.clone(), k.into()], context);
@@ -585,8 +592,8 @@ impl Map {
             let mut key = if_abrupt_close_iterator!(key, iterator, context);
 
             // h. Else,
-            //     i. Assert: keyCoercion is zero.
-            //     ii. If key is -0𝔽, set key to +0𝔽.
+            //     i. Assert: keyCoercion is collection.
+            //     ii. Set key to CanonicalizeKeyedCollectionKey(key).
             if key.as_number() == Some(-0.0) {
                 key = 0.into();
             }
@@ -632,31 +639,20 @@ impl Map {
 pub(crate) fn add_entries_from_iterable(
     target: &JsObject,
     iterable: &JsValue,
-    adder: &JsValue,
+    adder: &JsFunction,
     context: &mut Context,
 ) -> JsResult<JsValue> {
-    // 1. If IsCallable(adder) is false, throw a TypeError exception.
-    let adder = adder.as_callable().ok_or_else(|| {
-        JsNativeError::typ().with_message("property `set` of `NewTarget` is not callable")
-    })?;
-
-    // 2. Let iteratorRecord be ? GetIterator(iterable).
-    let mut iterator_record = iterable.get_iterator(context, None, None)?;
-
-    // 3. Repeat,
-    loop {
-        // a. Let next be ? IteratorStep(iteratorRecord).
-        // b. If next is false, return target.
-        // c. Let nextItem be ? IteratorValue(next).
-        if iterator_record.step(context)? {
-            return Ok(target.clone().into());
-        };
-
-        let next_item = iterator_record.value(context)?;
-
-        let Some(next_item) = next_item.as_object() else {
-            // d. If Type(nextItem) is not Object, then
+    // 1. Let iteratorRecord be ? GetIterator(iterable, sync).
+    let mut iterator_record = iterable.get_iterator(IteratorHint::Sync, context)?;
+
+    // 2. Repeat,
+    //     a. Let next be ? IteratorStepValue(iteratorRecord).
+    //     b. If next is done, return target.
+    while let Some(next) = iterator_record.step_value(context)? {
+        let Some(next) = next.as_object() else {
+            //     c. If next is not an Object, then
             //         i. Let error be ThrowCompletion(a newly created TypeError object).
+            //         ii. Return ? IteratorClose(iteratorRecord, error).
             let err = Err(JsNativeError::typ()
                 .with_message("cannot get key and value from primitive item of `iterable`")
                 .into());
@@ -665,26 +661,19 @@ pub(crate) fn add_entries_from_iterable(
             return iterator_record.close(err, context);
         };
 
-        // e. Let k be Get(nextItem, "0").
-        // f. IfAbruptCloseIterator(k, iteratorRecord).
-        let key = match next_item.get(0, context) {
-            Ok(val) => val,
-            err => return iterator_record.close(err, context),
-        };
+        //     d. Let k be Completion(Get(next, "0")).
+        //     e. IfAbruptCloseIterator(k, iteratorRecord).
+        let key = if_abrupt_close_iterator!(next.get(0, context), iterator_record, context);
 
-        // g. Let v be Get(nextItem, "1").
-        // h. IfAbruptCloseIterator(v, iteratorRecord).
-        let value = match next_item.get(1, context) {
-            Ok(val) => val,
-            err => return iterator_record.close(err, context),
-        };
+        //     f. Let v be Completion(Get(next, "1")).
+        //     g. IfAbruptCloseIterator(v, iteratorRecord).
+        let value = if_abrupt_close_iterator!(next.get(1, context), iterator_record, context);
 
-        // i. Let status be Call(adder, target, « k, v »).
+        //     h. Let status be Completion(Call(adder, target, « k, v »)).
+        //     i. IfAbruptCloseIterator(status, iteratorRecord).
         let status = adder.call(&target.clone().into(), &[key, value], context);
-
-        // j. IfAbruptCloseIterator(status, iteratorRecord).
-        if status.is_err() {
-            return iterator_record.close(status, context);
-        }
+        if_abrupt_close_iterator!(status, iterator_record, context);
     }
+
+    Ok(target.clone().into())
 }

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

@@ -17,7 +17,7 @@ use super::{
     error::ErrorObject, Array, BuiltInBuilder, BuiltInConstructor, Date, IntrinsicObject, RegExp,
 };
 use crate::{
-    builtins::{map, BuiltInObject},
+    builtins::{iterable::IteratorHint, map, BuiltInObject},
     context::intrinsics::{Intrinsics, StandardConstructor, StandardConstructors},
     error::JsNativeError,
     js_string,
@@ -1339,7 +1339,7 @@ impl OrdinaryObject {
         let adder = closure.length(2).name("").build();
 
         // 6. Return ? AddEntriesFromIterable(obj, iterable, adder).
-        map::add_entries_from_iterable(&obj, iterable, &adder.into(), context)
+        map::add_entries_from_iterable(&obj, iterable, &adder, context)
     }
 
     /// [`Object.groupBy ( items, callbackfn )`][spec]
@@ -1362,7 +1362,7 @@ impl OrdinaryObject {
         // 1. Let groups be ? GroupBy(items, callbackfn, property).
 
         // `GroupBy`
-        // https://tc39.es/proposal-array-grouping/#sec-group-by
+        // https://tc39.es/ecma262/#sec-groupby
         // inlined to change the key type.
 
         // 1. Perform ? RequireObjectCoercible(items).
@@ -1377,8 +1377,8 @@ impl OrdinaryObject {
         let mut groups: IndexMap<PropertyKey, Vec<JsValue>, BuildHasherDefault<FxHasher>> =
             IndexMap::default();
 
-        // 4. Let iteratorRecord be ? GetIterator(items).
-        let mut iterator = items.get_iterator(context, None, None)?;
+        // 4. Let iteratorRecord be ? GetIterator(items, sync).
+        let mut iterator = items.get_iterator(IteratorHint::Sync, context)?;
 
         // 5. Let k be 0.
         let mut k = 0u64;
@@ -1396,17 +1396,15 @@ impl OrdinaryObject {
                 return iterator.close(Err(error), context);
             }
 
-            // b. Let next be ? IteratorStep(iteratorRecord).
-            let done = iterator.step(context)?;
-
+            // b. Let next be ? IteratorStepValue(iteratorRecord).
+            let Some(next) = iterator.step_value(context)? else {
                 // c. If next is false, then
-            if done {
                 // i. Return groups.
                 break;
-            }
+            };
 
-            // d. Let value be ? IteratorValue(next).
-            let value = iterator.value(context)?;
+            // d. Let value be next.
+            let value = next;
 
             // e. Let key be Completion(Call(callbackfn, undefined, « value, 𝔽(k) »)).
             let key = callback.call(&JsValue::undefined(), &[value.clone(), k.into()], context);

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

@@ -3,7 +3,10 @@
 #[cfg(test)]
 mod tests;
 
-use super::{iterable::IteratorRecord, BuiltInBuilder, BuiltInConstructor, IntrinsicObject};
+use super::{
+    iterable::{IteratorHint, IteratorRecord},
+    BuiltInBuilder, BuiltInConstructor, IntrinsicObject,
+};
 use crate::{
     builtins::{Array, BuiltInObject},
     context::intrinsics::{Intrinsics, StandardConstructor, StandardConstructors},
@@ -581,8 +584,10 @@ impl Promise {
         let promise_resolve =
             if_abrupt_reject_promise!(promise_resolve, promise_capability, context);
 
-        // 5. Let iteratorRecord be Completion(GetIterator(iterable)).
-        let iterator_record = args.get_or_undefined(0).get_iterator(context, None, None);
+        // 5. Let iteratorRecord be Completion(GetIterator(iterable, sync)).
+        let iterator_record = args
+            .get_or_undefined(0)
+            .get_iterator(IteratorHint::Sync, context);
 
         // 6. IfAbruptRejectPromise(iteratorRecord, promiseCapability).
         let mut iterator_record =
@@ -649,56 +654,22 @@ impl Promise {
         let mut index = 0;
 
         // 4. Repeat,
-        loop {
-            // a. Let next be Completion(IteratorStep(iteratorRecord)).
-            // b. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
-            // c. ReturnIfAbrupt(next).
-            let done = iterator_record.step(context)?;
-
-            // d. If next is false, then
-            // i. Set iteratorRecord.[[Done]] to true.
-            if done {
-                // ii. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
-                remaining_elements_count.set(remaining_elements_count.get() - 1);
-
-                // iii. If remainingElementsCount.[[Value]] is 0, then
-                if remaining_elements_count.get() == 0 {
-                    // 1. Let valuesArray be CreateArrayFromList(values).
-                    let values_array =
-                        Array::create_array_from_list(values.borrow().iter().cloned(), context);
-
-                    // 2. Perform ? Call(resultCapability.[[Resolve]], undefined, « valuesArray »).
-                    result_capability.functions.resolve.call(
-                        &JsValue::undefined(),
-                        &[values_array.into()],
-                        context,
-                    )?;
-                }
-
-                // iv. Return resultCapability.[[Promise]].
-                return Ok(result_capability.promise.clone());
-            }
-
-            // e. Let nextValue be Completion(IteratorValue(next)).
-            // f. If nextValue is an abrupt completion, set iteratorRecord.[[Done]] to true.
-            // g. ReturnIfAbrupt(nextValue).
-            let next_value = iterator_record.value(context)?;
-
-            // h. Append undefined to values.
+        while let Some(next) = iterator_record.step_value(context)? {
+            // c. Append undefined to values.
             values.borrow_mut().push(JsValue::Undefined);
 
-            // i. Let nextPromise be ? Call(promiseResolve, constructor, « nextValue »).
+            // d. Let nextPromise be ? Call(promiseResolve, constructor, « next »).
             let next_promise =
-                promise_resolve.call(&constructor.clone().into(), &[next_value], context)?;
-
-            // j. Let steps be the algorithm steps defined in Promise.all Resolve Element Functions.
-            // k. Let length be the number of non-optional parameters of the function definition in Promise.all Resolve Element Functions.
-            // l. Let onFulfilled be CreateBuiltinFunction(steps, length, "", « [[AlreadyCalled]], [[Index]], [[Values]], [[Capability]], [[RemainingElements]] »).
-            // m. Set onFulfilled.[[AlreadyCalled]] to false.
-            // n. Set onFulfilled.[[Index]] to index.
-            // o. Set onFulfilled.[[Values]] to values.
-            // p. Set onFulfilled.[[Capability]] to resultCapability.
-            // q. Set onFulfilled.[[RemainingElements]] to remainingElementsCount.
+                promise_resolve.call(&constructor.clone().into(), &[next], context)?;
+
+            // e. Let steps be the algorithm steps defined in Promise.all Resolve Element Functions.
+            // f. Let length be the number of non-optional parameters of the function definition in Promise.all Resolve Element Functions.
+            // g. Let onFulfilled be CreateBuiltinFunction(steps, length, "", « [[AlreadyCalled]], [[Index]], [[Values]], [[Capability]], [[RemainingElements]] »).
+            // h. Set onFulfilled.[[AlreadyCalled]] to false.
+            // i. Set onFulfilled.[[Index]] to index.
+            // j. Set onFulfilled.[[Values]] to values.
+            // k. Set onFulfilled.[[Capability]] to resultCapability.
+            // l. Set onFulfilled.[[RemainingElements]] to remainingElementsCount.
             let on_fulfilled = FunctionObjectBuilder::new(
                 context.realm(),
                 NativeFunction::from_copy_closure_with_captures(
@@ -761,10 +732,10 @@ impl Promise {
             .constructor(false)
             .build();
 
-            // r. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] + 1.
+            // m. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] + 1.
             remaining_elements_count.set(remaining_elements_count.get() + 1);
 
-            // s. Perform ? Invoke(nextPromise, "then", « onFulfilled, resultCapability.[[Reject]] »).
+            // n. Perform ? Invoke(nextPromise, "then", « onFulfilled, resultCapability.[[Reject]] »).
             next_promise.invoke(
                 js_str!("then"),
                 &[
@@ -774,9 +745,30 @@ impl Promise {
                 context,
             )?;
 
-            // t. Set index to index + 1.
+            // o. Set index to index + 1.
             index += 1;
         }
+
+        // b. If next is done, then
+        //     i. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
+        remaining_elements_count.set(remaining_elements_count.get() - 1);
+
+        //     ii. If remainingElementsCount.[[Value]] = 0, then
+        if remaining_elements_count.get() == 0 {
+            // 1. Let valuesArray be CreateArrayFromList(values).
+            let values_array =
+                Array::create_array_from_list(values.borrow().iter().cloned(), context);
+
+            // 2. Perform ? Call(resultCapability.[[Resolve]], undefined, « valuesArray »).
+            result_capability.functions.resolve.call(
+                &JsValue::undefined(),
+                &[values_array.into()],
+                context,
+            )?;
+        }
+
+        //     iii. Return resultCapability.[[Promise]].
+        Ok(result_capability.promise.clone())
     }
 
     /// `Promise.allSettled ( iterable )`
@@ -807,8 +799,10 @@ impl Promise {
         let promise_resolve =
             if_abrupt_reject_promise!(promise_resolve, promise_capability, context);
 
-        // 5. Let iteratorRecord be Completion(GetIterator(iterable)).
-        let iterator_record = args.get_or_undefined(0).get_iterator(context, None, None);
+        // 5. Let iteratorRecord be Completion(GetIterator(iterable, sync)).
+        let iterator_record = args
+            .get_or_undefined(0)
+            .get_iterator(IteratorHint::Sync, context);
 
         // 6. IfAbruptRejectPromise(iteratorRecord, promiseCapability).
         let mut iterator_record =
@@ -875,59 +869,23 @@ impl Promise {
         let mut index = 0;
 
         // 4. Repeat,
-        loop {
-            // a. Let next be Completion(IteratorStep(iteratorRecord)).
-            // b. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
-            // c. ReturnIfAbrupt(next).
-            let done = iterator_record.step(context)?;
-
-            // d. If next is false, then
-            if done {
-                // i. Set iteratorRecord.[[Done]] to true.
-                // ii. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
-                remaining_elements_count.set(remaining_elements_count.get() - 1);
-
-                // iii. If remainingElementsCount.[[Value]] is 0, then
-                if remaining_elements_count.get() == 0 {
-                    // 1. Let valuesArray be CreateArrayFromList(values).
-                    let values_array = Array::create_array_from_list(
-                        values.borrow().as_slice().iter().cloned(),
-                        context,
-                    );
-
-                    // 2. Perform ? Call(resultCapability.[[Resolve]], undefined, « valuesArray »).
-                    result_capability.functions.resolve.call(
-                        &JsValue::undefined(),
-                        &[values_array.into()],
-                        context,
-                    )?;
-                }
-
-                // iv. Return resultCapability.[[Promise]].
-                return Ok(result_capability.promise.clone());
-            }
-
-            // e. Let nextValue be Completion(IteratorValue(next)).
-            // f. If nextValue is an abrupt completion, set iteratorRecord.[[Done]] to true.
-            // g. ReturnIfAbrupt(nextValue).
-            let next_value = iterator_record.value(context)?;
-
-            // h. Append undefined to values.
+        while let Some(next) = iterator_record.step_value(context)? {
+            // c. Append undefined to values.
             values.borrow_mut().push(JsValue::undefined());
 
-            // i. Let nextPromise be ? Call(promiseResolve, constructor, « nextValue »).
+            // d. Let nextPromise be ? Call(promiseResolve, constructor, « next »).
             let next_promise =
-                promise_resolve.call(&constructor.clone().into(), &[next_value], context)?;
-
-            // j. Let stepsFulfilled be the algorithm steps defined in Promise.allSettled Resolve Element Functions.
-            // k. Let lengthFulfilled be the number of non-optional parameters of the function definition in Promise.allSettled Resolve Element Functions.
-            // l. Let onFulfilled be CreateBuiltinFunction(stepsFulfilled, lengthFulfilled, "", « [[AlreadyCalled]], [[Index]], [[Values]], [[Capability]], [[RemainingElements]] »).
-            // m. Let alreadyCalled be the Record { [[Value]]: false }.
-            // n. Set onFulfilled.[[AlreadyCalled]] to alreadyCalled.
-            // o. Set onFulfilled.[[Index]] to index.
-            // p. Set onFulfilled.[[Values]] to values.
-            // q. Set onFulfilled.[[Capability]] to resultCapability.
-            // r. Set onFulfilled.[[RemainingElements]] to remainingElementsCount.
+                promise_resolve.call(&constructor.clone().into(), &[next], context)?;
+
+            // e. Let stepsFulfilled be the algorithm steps defined in Promise.allSettled Resolve Element Functions.
+            // f. Let lengthFulfilled be the number of non-optional parameters of the function definition in Promise.allSettled Resolve Element Functions.
+            // g. Let onFulfilled be CreateBuiltinFunction(stepsFulfilled, lengthFulfilled, "", « [[AlreadyCalled]], [[Index]], [[Values]], [[Capability]], [[RemainingElements]] »).
+            // h. Let alreadyCalled be the Record { [[Value]]: false }.
+            // i. Set onFulfilled.[[AlreadyCalled]] to alreadyCalled.
+            // j. Set onFulfilled.[[Index]] to index.
+            // k. Set onFulfilled.[[Values]] to values.
+            // l. Set onFulfilled.[[Capability]] to resultCapability.
+            // m. Set onFulfilled.[[RemainingElements]] to remainingElementsCount.
             let on_fulfilled = FunctionObjectBuilder::new(
                 context.realm(),
                 NativeFunction::from_copy_closure_with_captures(
@@ -1010,14 +968,14 @@ impl Promise {
             .constructor(false)
             .build();
 
-            // s. Let stepsRejected be the algorithm steps defined in Promise.allSettled Reject Element Functions.
-            // t. Let lengthRejected be the number of non-optional parameters of the function definition in Promise.allSettled Reject Element Functions.
-            // u. Let onRejected be CreateBuiltinFunction(stepsRejected, lengthRejected, "", « [[AlreadyCalled]], [[Index]], [[Values]], [[Capability]], [[RemainingElements]] »).
-            // v. Set onRejected.[[AlreadyCalled]] to alreadyCalled.
-            // w. Set onRejected.[[Index]] to index.
-            // x. Set onRejected.[[Values]] to values.
-            // y. Set onRejected.[[Capability]] to resultCapability.
-            // z. Set onRejected.[[RemainingElements]] to remainingElementsCount.
+            // n. Let stepsRejected be the algorithm steps defined in Promise.allSettled Reject Element Functions.
+            // o. Let lengthRejected be the number of non-optional parameters of the function definition in Promise.allSettled Reject Element Functions.
+            // p. Let onRejected be CreateBuiltinFunction(stepsRejected, lengthRejected, "", « [[AlreadyCalled]], [[Index]], [[Values]], [[Capability]], [[RemainingElements]] »).
+            // q. Set onRejected.[[AlreadyCalled]] to alreadyCalled.
+            // r. Set onRejected.[[Index]] to index.
+            // s. Set onRejected.[[Values]] to values.
+            // t. Set onRejected.[[Capability]] to resultCapability.
+            // u. Set onRejected.[[RemainingElements]] to remainingElementsCount.
             let on_rejected = FunctionObjectBuilder::new(
                 context.realm(),
                 NativeFunction::from_copy_closure_with_captures(
@@ -1100,19 +1058,40 @@ impl Promise {
             .constructor(false)
             .build();
 
-            // aa. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] + 1.
+            // v. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] + 1.
             remaining_elements_count.set(remaining_elements_count.get() + 1);
 
-            // ab. Perform ? Invoke(nextPromise, "then", « onFulfilled, onRejected »).
+            // w. Perform ? Invoke(nextPromise, "then", « onFulfilled, onRejected »).
             next_promise.invoke(
                 js_str!("then"),
                 &[on_fulfilled.into(), on_rejected.into()],
                 context,
             )?;
 
-            // ac. Set index to index + 1.
+            // x. Set index to index + 1.
             index += 1;
         }
+
+        // b. If next is done, then
+        //     i. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
+        remaining_elements_count.set(remaining_elements_count.get() - 1);
+
+        //     ii. If remainingElementsCount.[[Value]] = 0, then
+        if remaining_elements_count.get() == 0 {
+            // 1. Let valuesArray be CreateArrayFromList(values).
+            let values_array =
+                Array::create_array_from_list(values.borrow().as_slice().iter().cloned(), context);
+
+            // 2. Perform ? Call(resultCapability.[[Resolve]], undefined, « valuesArray »).
+            result_capability.functions.resolve.call(
+                &JsValue::undefined(),
+                &[values_array.into()],
+                context,
+            )?;
+        }
+
+        //     iii. Return resultCapability.[[Promise]].
+        Ok(result_capability.promise.clone())
     }
 
     /// `Promise.any ( iterable )`
@@ -1143,8 +1122,10 @@ impl Promise {
         let promise_resolve =
             if_abrupt_reject_promise!(promise_resolve, promise_capability, context);
 
-        // 5. Let iteratorRecord be Completion(GetIterator(iterable)).
-        let iterator_record = args.get_or_undefined(0).get_iterator(context, None, None);
+        // 5. Let iteratorRecord be Completion(GetIterator(iterable, sync)).
+        let iterator_record = args
+            .get_or_undefined(0)
+            .get_iterator(IteratorHint::Sync, context);
 
         // 6. IfAbruptRejectPromise(iteratorRecord, promiseCapability).
         let mut iterator_record =
@@ -1211,61 +1192,23 @@ impl Promise {
         let mut index = 0;
 
         // 4. Repeat,
-        loop {
-            // a. Let next be Completion(IteratorStep(iteratorRecord)).
-            // b. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
-            // c. ReturnIfAbrupt(next).
-            let done = iterator_record.step(context)?;
-
-            // d. If next is false, then
-            if done {
-                // i. Set iteratorRecord.[[Done]] to true.
-
-                // ii. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
-                remaining_elements_count.set(remaining_elements_count.get() - 1);
-
-                // iii. If remainingElementsCount.[[Value]] is 0, then
-                if remaining_elements_count.get() == 0 {
-                    // 1. Let error be a newly created AggregateError object.
-                    // 2. Perform ! DefinePropertyOrThrow(error, "errors", PropertyDescriptor { [[Configurable]]: true, [[Enumerable]]: false, [[Writable]]: true, [[Value]]: CreateArrayFromList(errors) }).
-                    let error = JsNativeError::aggregate(
-                        errors
-                            .borrow()
-                            .iter()
-                            .cloned()
-                            .map(JsError::from_opaque)
-                            .collect(),
-                    )
-                    .with_message("no promise in Promise.any was fulfilled.");
-
-                    // 3. Return ThrowCompletion(error).
-                    return Err(error.into());
-                }
-
-                // iv. Return resultCapability.[[Promise]].
-                return Ok(result_capability.promise.clone());
-            }
-
-            // e. Let nextValue be Completion(IteratorValue(next)).
-            // f. If nextValue is an abrupt completion, set iteratorRecord.[[Done]] to true.
-            // g. ReturnIfAbrupt(nextValue).
-            let next_value = iterator_record.value(context)?;
-
-            // h. Append undefined to errors.
+        //     a. Let next be ? IteratorStepValue(iteratorRecord).
+        while let Some(next) = iterator_record.step_value(context)? {
+            // c. Append undefined to errors.
             errors.borrow_mut().push(JsValue::undefined());
 
-            // i. Let nextPromise be ? Call(promiseResolve, constructor, « nextValue »).
+            // d. Let nextPromise be ? Call(promiseResolve, constructor, « next »).
             let next_promise =
-                promise_resolve.call(&constructor.clone().into(), &[next_value], context)?;
-
-            // j. Let stepsRejected be the algorithm steps defined in Promise.any Reject Element Functions.
-            // k. Let lengthRejected be the number of non-optional parameters of the function definition in Promise.any Reject Element Functions.
-            // l. Let onRejected be CreateBuiltinFunction(stepsRejected, lengthRejected, "", « [[AlreadyCalled]], [[Index]], [[Errors]], [[Capability]], [[RemainingElements]] »).
-            // m. Set onRejected.[[AlreadyCalled]] to false.
-            // n. Set onRejected.[[Index]] to index.
-            // o. Set onRejected.[[Errors]] to errors.
-            // p. Set onRejected.[[Capability]] to resultCapability.
-            // q. Set onRejected.[[RemainingElements]] to remainingElementsCount.
+                promise_resolve.call(&constructor.clone().into(), &[next], context)?;
+
+            // e. Let stepsRejected be the algorithm steps defined in Promise.any Reject Element Functions.
+            // f. Let lengthRejected be the number of non-optional parameters of the function definition in Promise.any Reject Element Functions.
+            // g. Let onRejected be CreateBuiltinFunction(stepsRejected, lengthRejected, "", « [[AlreadyCalled]], [[Index]], [[Errors]], [[Capability]], [[RemainingElements]] »).
+            // h. Set onRejected.[[AlreadyCalled]] to false.
+            // i. Set onRejected.[[Index]] to index.
+            // j. Set onRejected.[[Errors]] to errors.
+            // k. Set onRejected.[[Capability]] to resultCapability.
+            // l. Set onRejected.[[RemainingElements]] to remainingElementsCount.
             let on_rejected = FunctionObjectBuilder::new(
                 context.realm(),
                 NativeFunction::from_copy_closure_with_captures(
@@ -1336,10 +1279,10 @@ impl Promise {
             .constructor(false)
             .build();
 
-            // r. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] + 1.
+            // m. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] + 1.
             remaining_elements_count.set(remaining_elements_count.get() + 1);
 
-            // s. Perform ? Invoke(nextPromise, "then", « resultCapability.[[Resolve]], onRejected »).
+            // n. Perform ? Invoke(nextPromise, "then", « resultCapability.[[Resolve]], onRejected »).
             next_promise.invoke(
                 js_str!("then"),
                 &[
@@ -1349,9 +1292,33 @@ impl Promise {
                 context,
             )?;
 
-            // t. Set index to index + 1.
+            // o. Set index to index + 1.
             index += 1;
         }
+
+        //     b. If next is done, then
+        //         i. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
+        remaining_elements_count.set(remaining_elements_count.get() - 1);
+        //         ii. If remainingElementsCount.[[Value]] = 0, then
+        if remaining_elements_count.get() == 0 {
+            // 1. Let error be a newly created AggregateError object.
+            let error = JsNativeError::aggregate(
+                errors
+                    .borrow()
+                    .iter()
+                    .cloned()
+                    .map(JsError::from_opaque)
+                    .collect(),
+            )
+            .with_message("no promise in Promise.any was fulfilled.");
+
+            // 2. Perform ! DefinePropertyOrThrow(error, "errors", PropertyDescriptor { [[Configurable]]: true, [[Enumerable]]: false, [[Writable]]: true, [[Value]]: CreateArrayFromList(errors) }).
+            // 3. Return ThrowCompletion(error).
+            return Err(error.into());
+        }
+
+        //         iii. Return resultCapability.[[Promise]].
+        Ok(result_capability.promise.clone())
     }
 
     /// `Promise.race ( iterable )`
@@ -1387,8 +1354,8 @@ impl Promise {
         let promise_resolve =
             if_abrupt_reject_promise!(promise_resolve, promise_capability, context);
 
-        // 5. Let iteratorRecord be Completion(GetIterator(iterable)).
-        let iterator_record = iterable.get_iterator(context, None, None);
+        // 5. Let iteratorRecord be Completion(GetIterator(iterable, sync)).
+        let iterator_record = iterable.get_iterator(IteratorHint::Sync, context);
 
         // 6. IfAbruptRejectPromise(iteratorRecord, promiseCapability).
         let mut iterator_record =
@@ -1440,29 +1407,13 @@ impl Promise {
         context: &mut Context,
     ) -> JsResult<JsObject> {
         let constructor = constructor.clone().into();
-        // 1. Repeat,
-        loop {
-            // a. Let next be Completion(IteratorStep(iteratorRecord)).
-            // b. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
-            // c. ReturnIfAbrupt(next).
-            let done = iterator_record.step(context)?;
-
-            if done {
-                // d. If next is false, then
-                // i. Set iteratorRecord.[[Done]] to true.
-                // ii. Return resultCapability.[[Promise]].
-                return Ok(result_capability.promise.clone());
-            }
-
-            // e. Let nextValue be Completion(IteratorValue(next)).
-            // f. If nextValue is an abrupt completion, set iteratorRecord.[[Done]] to true.
-            // g. ReturnIfAbrupt(nextValue).
-            let next_value = iterator_record.value(context)?;
 
-            // h. Let nextPromise be ? Call(promiseResolve, constructor, « nextValue »).
-            let next_promise = promise_resolve.call(&constructor, &[next_value], context)?;
-
-            // i. Perform ? Invoke(nextPromise, "then", « resultCapability.[[Resolve]], resultCapability.[[Reject]] »).
+        // 1. Repeat,
+        //     a. Let next be ? IteratorStepValue(iteratorRecord).
+        while let Some(next) = iterator_record.step_value(context)? {
+            // c. Let nextPromise be ? Call(promiseResolve, constructor, « next »).
+            let next_promise = promise_resolve.call(&constructor, &[next], context)?;
+            // d. Perform ? Invoke(nextPromise, "then", « resultCapability.[[Resolve]], resultCapability.[[Reject]] »).
             next_promise.invoke(
                 js_str!("then"),
                 &[
@@ -1472,6 +1423,10 @@ impl Promise {
                 context,
             )?;
         }
+
+        //     b. If next is done, then
+        //         i. Return resultCapability.[[Promise]].
+        Ok(result_capability.promise.clone())
     }
 
     /// `Promise.reject ( r )`

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

@@ -36,6 +36,8 @@ use num_traits::Zero;
 
 pub(crate) use set_iterator::SetIterator;
 
+use super::iterable::IteratorHint;
+
 #[derive(Debug, Clone)]
 pub(crate) struct Set;
 
@@ -110,6 +112,9 @@ impl BuiltInConstructor for Set {
     const STANDARD_CONSTRUCTOR: fn(&StandardConstructors) -> &StandardConstructor =
         StandardConstructors::set;
 
+    /// [`Set ( [ iterable ] )`][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-set-iterable
     fn constructor(
         new_target: &JsValue,
         args: &[JsValue],
@@ -146,26 +151,20 @@ impl BuiltInConstructor for Set {
             JsNativeError::typ().with_message("'add' of 'newTarget' is not a function")
         })?;
 
-        // 7. Let iteratorRecord be ? GetIterator(iterable).
-        let mut iterator_record = iterable.clone().get_iterator(context, None, None)?;
+        // 7. Let iteratorRecord be ? GetIterator(iterable, sync).
+        let mut iterator_record = iterable.clone().get_iterator(IteratorHint::Sync, context)?;
 
         // 8. Repeat,
-        //     a. Let next be ? IteratorStep(iteratorRecord).
-        //     b. If next is false, return set.
-        //     c. Let nextValue be ? IteratorValue(next).
-        //     d. Let status be Completion(Call(adder, set, « nextValue »)).
-        //     e. IfAbruptCloseIterator(status, iteratorRecord).
-        while !iterator_record.step(context)? {
-            let next = iterator_record.value(context)?;
-            // c
-
-            // d, e
+        //     a. Let next be ? IteratorStepValue(iteratorRecord).
+        while let Some(next) = iterator_record.step_value(context)? {
+            // c. Let status be Completion(Call(adder, set, « next »)).
             if let Err(status) = adder.call(&set.clone().into(), &[next], context) {
+                // d. IfAbruptCloseIterator(status, iteratorRecord).
                 return iterator_record.close(Err(status), context);
             }
         }
 
-        // 8.b
+        //     b. If next is done, return set.
         Ok(set.into())
     }
 }

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

@@ -189,28 +189,26 @@ pub(crate) fn _iterator_to_list_of_types(
     // 1. Let values be a new empty List.
     let mut values = Vec::new();
 
-    // 2. Let next be true.
-    // 3. Repeat, while next is not false,
-    // a. Set next to ? IteratorStep(iteratorRecord).
-    // b. If next is not false, then
-    while iterator.step(context)? {
-        // i. Let nextValue be ? IteratorValue(next).
-        let next_value = iterator.value(context)?;
-        // ii. If Type(nextValue) is not an element of elementTypes, then
-        if element_types.contains(&next_value.get_type()) {
-            // 1. Let completion be ThrowCompletion(a newly created TypeError object).
+    // 2. Repeat,
+    //     a. Let next be ? IteratorStepValue(iteratorRecord).
+    while let Some(next) = iterator.step_value(context)? {
+        // c. If Type(next) is not an element of elementTypes, then
+
+        if element_types.contains(&next.get_type()) {
+            //     i. Let completion be ThrowCompletion(a newly created TypeError object).
             let completion = JsNativeError::typ()
                 .with_message("IteratorNext is not within allowed type values.");
 
-            // NOTE: The below should return as we are forcing a ThrowCompletion.
-            // 2. Return ? IteratorClose(iteratorRecord, completion).
+            //     ii. Return ? IteratorClose(iteratorRecord, completion).
             let _never = iterator.close(Err(completion.into()), context)?;
         }
-        // iii. Append nextValue to the end of the List values.
-        values.push(next_value);
+
+        // d. Append next to the end of the List values.
+        values.push(next);
     }
 
-    // 4. Return values.
+    // b. If next is done, then
+    //     i. Return values.
     Ok(values)
 }
 

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

@@ -16,7 +16,6 @@ use crate::{
             utils::{memcpy, memmove, SliceRefMut},
             ArrayBuffer, BufferObject,
         },
-        iterable::iterable_to_list,
         Array, BuiltInBuilder, BuiltInConstructor, BuiltInObject, IntrinsicObject,
     },
     context::intrinsics::{Intrinsics, StandardConstructor, StandardConstructors},
@@ -228,7 +227,9 @@ impl BuiltinTypedArray {
         // 6. If usingIterator is not undefined, then
         if let Some(using_iterator) = using_iterator {
             // a. Let values be ? IterableToList(source, usingIterator).
-            let values = iterable_to_list(context, source, Some(using_iterator))?;
+            let values = source
+                .get_iterator_from_method(&using_iterator, context)?
+                .into_list(context)?;
 
             // b. Let len be the number of elements in values.
             // c. Let targetObj be ? TypedArrayCreate(C, « 𝔽(len) »).

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

@@ -13,10 +13,7 @@
 //! [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
 
 use crate::{
-    builtins::{
-        iterable::iterable_to_list, BuiltInBuilder, BuiltInConstructor, BuiltInObject,
-        IntrinsicObject,
-    },
+    builtins::{BuiltInBuilder, BuiltInConstructor, BuiltInObject, IntrinsicObject},
     context::intrinsics::{Intrinsics, StandardConstructor, StandardConstructors},
     error::JsNativeError,
     js_string,
@@ -199,13 +196,14 @@ impl<T: TypedArrayMarker> BuiltInConstructor for T {
         // either a [[TypedArrayName]] or an [[ArrayBufferData]] internal slot.
 
         // 2. Let usingIterator be ? GetMethod(firstArgument, @@iterator).
-
         let using_iterator = first_argument.get_method(JsSymbol::iterator(), context)?;
 
         // 3. If usingIterator is not undefined, then
         if let Some(using_iterator) = using_iterator {
-            // a. Let values be ? IterableToList(firstArgument, usingIterator).
-            let values = iterable_to_list(context, &first_argument.into(), Some(using_iterator))?;
+            // a. Let values be ? IteratorToList(? GetIteratorFromMethod(firstArgument, usingIterator)).
+            let values = JsValue::from(first_argument.clone())
+                .get_iterator_from_method(&using_iterator, context)?
+                .into_list(context)?;
 
             // b. Perform ? InitializeTypedArrayFromList(O, values).
             BuiltinTypedArray::initialize_from_list::<T>(proto, values, context)

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

@@ -101,14 +101,11 @@ impl BuiltInConstructor for WeakMap {
         }
 
         // 5. Let adder be ? Get(map, "set").
-        let adder = map.get(js_str!("set"), context)?;
-
         // 6. If IsCallable(adder) is false, throw a TypeError exception.
-        if !adder.is_callable() {
-            return Err(JsNativeError::typ()
-                .with_message("WeakMap: 'add' is not a function")
-                .into());
-        }
+        let adder = map
+            .get(js_str!("set"), context)?
+            .as_function()
+            .ok_or_else(|| JsNativeError::typ().with_message("WeakMap: 'add' is not a function"))?;
 
         // 7. Return ? AddEntriesFromIterable(map, iterable, adder).
         add_entries_from_iterable(&map, iterable, &adder, context)

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

@@ -22,6 +22,8 @@ use boa_gc::{Finalize, Trace};
 use boa_macros::js_str;
 use boa_profiler::Profiler;
 
+use super::iterable::IteratorHint;
+
 type NativeWeakSet = boa_gc::WeakMap<ErasedVTableObject, ()>;
 
 #[derive(Debug, Trace, Finalize)]
@@ -104,23 +106,20 @@ impl BuiltInConstructor for WeakSet {
             .as_callable()
             .ok_or_else(|| JsNativeError::typ().with_message("WeakSet: 'add' is not a function"))?;
 
-        // 7. Let iteratorRecord be ? GetIterator(iterable).
-        let mut iterator_record = iterable.clone().get_iterator(context, None, None)?;
+        // 7. Let iteratorRecord be ? GetIterator(iterable, sync).
+        let mut iterator_record = iterable.clone().get_iterator(IteratorHint::Sync, context)?;
 
         // 8. Repeat,
-        // a. Let next be ? IteratorStep(iteratorRecord).
-        while !iterator_record.step(context)? {
-            // c. Let nextValue be ? IteratorValue(next).
-            let next = iterator_record.value(context)?;
-
-            // d. Let status be Completion(Call(adder, set, « nextValue »)).
-            // e. IfAbruptCloseIterator(status, iteratorRecord).
+        //     a. Let next be ? IteratorStepValue(iteratorRecord).
+        while let Some(next) = iterator_record.step_value(context)? {
+            //     c. Let status be Completion(Call(adder, set, « next »)).
             if let Err(status) = adder.call(&weak_set.clone().into(), &[next], context) {
+                //     d. IfAbruptCloseIterator(status, iteratorRecord).
                 return iterator_record.close(Err(status), context);
             }
         }
 
-        // b. If next is false, return set.
+        //     b. If next is done, return set.
         Ok(weak_set.into())
     }
 }

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

@@ -1,7 +1,10 @@
 //! A Rust API wrapper for Boa's `Map` Builtin ECMAScript Object
 use crate::{
-    builtins::map::{add_entries_from_iterable, ordered_map::OrderedMap},
-    builtins::Map,
+    builtins::{
+        iterable::IteratorHint,
+        map::{add_entries_from_iterable, ordered_map::OrderedMap},
+        Map,
+    },
     error::JsNativeError,
     object::{JsFunction, JsMapIterator, JsObject},
     value::TryFromJs,
@@ -126,8 +129,11 @@ impl JsMap {
 
         // Let adder be Get(map, "set") per spec. This action should not fail with default map.
         let adder = map
-            .get(js_str!("set"), context)
-            .expect("creating a map with the default prototype must not fail");
+            .get(js_str!("set"), context)?
+            .as_function()
+            .ok_or_else(|| {
+                JsNativeError::typ().with_message("property `set` on new `Map` must be callable")
+            })?;
 
         let _completion_record = add_entries_from_iterable(&map, iterable, &adder, context)?;
 
@@ -199,7 +205,7 @@ impl JsMap {
     #[inline]
     pub fn entries(&self, context: &mut Context) -> JsResult<JsMapIterator> {
         let iterator_record = Map::entries(&self.inner.clone().into(), &[], context)?
-            .get_iterator(context, None, None)?;
+            .get_iterator(IteratorHint::Sync, context)?;
         let map_iterator_object = iterator_record.iterator();
         JsMapIterator::from_object(map_iterator_object.clone())
     }
@@ -208,7 +214,7 @@ impl JsMap {
     #[inline]
     pub fn keys(&self, context: &mut Context) -> JsResult<JsMapIterator> {
         let iterator_record = Map::keys(&self.inner.clone().into(), &[], context)?
-            .get_iterator(context, None, None)?;
+            .get_iterator(IteratorHint::Sync, context)?;
         let map_iterator_object = iterator_record.iterator();
         JsMapIterator::from_object(map_iterator_object.clone())
     }
@@ -400,7 +406,7 @@ impl JsMap {
     #[inline]
     pub fn values(&self, context: &mut Context) -> JsResult<JsMapIterator> {
         let iterator_record = Map::values(&self.inner.clone().into(), &[], context)?
-            .get_iterator(context, None, None)?;
+            .get_iterator(IteratorHint::Sync, context)?;
         let map_iterator_object = iterator_record.iterator();
         JsMapIterator::from_object(map_iterator_object.clone())
     }

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

@@ -4,7 +4,7 @@ use std::ops::Deref;
 use boa_gc::{Finalize, Trace};
 
 use crate::{
-    builtins::{set::ordered_set::OrderedSet, Set},
+    builtins::{iterable::IteratorHint, set::ordered_set::OrderedSet, Set},
     error::JsNativeError,
     object::{JsFunction, JsObject, JsSetIterator},
     value::TryFromJs,
@@ -104,7 +104,7 @@ impl JsSet {
     #[inline]
     pub fn values(&self, context: &mut Context) -> JsResult<JsSetIterator> {
         let iterator_object = Set::values(&self.inner.clone().into(), &[JsValue::Null], context)?
-            .get_iterator(context, None, None)?;
+            .get_iterator(IteratorHint::Sync, context)?;
 
         JsSetIterator::from_object(iterator_object.iterator().clone())
     }
@@ -117,7 +117,7 @@ impl JsSet {
     #[inline]
     pub fn keys(&self, context: &mut Context) -> JsResult<JsSetIterator> {
         let iterator_object = Set::values(&self.inner.clone().into(), &[JsValue::Null], context)?
-            .get_iterator(context, None, None)?;
+            .get_iterator(IteratorHint::Sync, context)?;
 
         JsSetIterator::from_object(iterator_object.iterator().clone())
     }

core/engine/src/vm/opcode/iteration/get.rs

@@ -18,7 +18,7 @@ impl Operation for GetIterator {
 
     fn execute(context: &mut Context) -> JsResult<CompletionType> {
         let object = context.vm.pop();
-        let iterator = object.get_iterator(context, None, None)?;
+        let iterator = object.get_iterator(IteratorHint::Sync, context)?;
         context.vm.frame_mut().iterators.push(iterator);
         Ok(CompletionType::Normal)
     }
@@ -38,7 +38,7 @@ impl Operation for GetAsyncIterator {
 
     fn execute(context: &mut Context) -> JsResult<CompletionType> {
         let object = context.vm.pop();
-        let iterator = object.get_iterator(context, Some(IteratorHint::Async), None)?;
+        let iterator = object.get_iterator(IteratorHint::Async, context)?;
         context.vm.frame_mut().iterators.push(iterator);
         Ok(CompletionType::Normal)
     }

core/engine/src/vm/opcode/push/array.rs

@@ -101,8 +101,7 @@ impl Operation for PushIteratorToArray {
             .expect("iterator stack should have at least an iterator");
         let array = context.vm.pop();
 
-        while !iterator.step(context)? {
-            let next = iterator.value(context)?;
+        while let Some(next) = iterator.step_value(context)? {
             Array::push(&array, &[next], context)?;
         }
 

test262_config.toml

@@ -1,4 +1,4 @@
-commit = "12307f5c20a4c4211e69823939fd1872212894c5"
+commit = "dde3050bdbfb8f425084077b6293563932d57ebc"
 
 [ignored]
 # Not implemented yet: