diff --git a/typescript/core/base.ts b/typescript/core/base.ts
index f101755b7..63d82913f 100644
--- a/typescript/core/base.ts
+++ b/typescript/core/base.ts
@@ -261,6 +261,10 @@ export interface _base {
 
     isWindow: (obj: any) => obj is Window;
 
+    deepClone: <T>(obj: T) => T;
+
+    deepExtend: merge['deepExtend'];
+
     isDeepMatch: (object: any, attrs: any) => boolean;
 
     contains: (obj: any[], target: any, fromIndex?: number) => boolean;
@@ -373,3 +377,17 @@ export interface _base {
 
     getTime: (...args: any[]) => number;
 }
+
+type merge = {
+    deepExtend<TObject, TSource>(object: TObject, source: TSource): TObject & TSource;
+
+    deepExtend<TObject, TSource1, TSource2>(object: TObject, source1: TSource1, source2: TSource2): TObject & TSource1 & TSource2;
+
+    deepExtend<TObject, TSource1, TSource2>(object: TObject, source1: TSource1, source2: TSource2): TObject & TSource1 & TSource2;
+
+    deepExtend<TObject, TSource1, TSource2, TSource3>(object: TObject, source1: TSource1, source2: TSource2, source3: TSource3): TObject & TSource1 & TSource2 & TSource3;
+
+    deepExtend<TObject, TSource1, TSource2, TSource3, TSource4>(object: TObject, source1: TSource1, source2: TSource2, source3: TSource3, source4: TSource4): TObject & TSource1 & TSource2 & TSource3 & TSource4;
+
+    deepExtend(object: any, ...otherArgs: any[]): any;
+}