diff --git a/codes/typescript/chapter_hashing/array_hash_map.ts b/codes/typescript/chapter_hashing/array_hash_map.ts
index d56fb8fd7..d5b5a9f80 100644
--- a/codes/typescript/chapter_hashing/array_hash_map.ts
+++ b/codes/typescript/chapter_hashing/array_hash_map.ts
@@ -24,7 +24,6 @@ class ArrayList {
 
   /* 新增和删除 */
   public set(key: number, val: string | null) {
-    this.isOutOfRange(key);
     if (val !== null) {
       this.elements[key] = new Entry(key, val);
     }
@@ -65,12 +64,6 @@ class ArrayList {
     }
     return arr;
   }
-
-  private isOutOfRange(key: number) {
-    if (key > this.elements.length - 1) {
-      throw new Error('Out of array range');
-    }
-  }
 }
 
 /* 基于数组简易实现的哈希表 */
diff --git a/docs/chapter_hashing/hash_map.md b/docs/chapter_hashing/hash_map.md
index 091e1242f..2fed2facd 100644
--- a/docs/chapter_hashing/hash_map.md
+++ b/docs/chapter_hashing/hash_map.md
@@ -536,7 +536,6 @@ $$
         
         /* 新增和删除 */
         public set(key: number, val: string | null) {
-            this.isOutOfRange(key);
             if (val !== null) {
                 this.elements[key] = new Entry(key, val);
             }
@@ -577,12 +576,6 @@ $$
             }
             return arr;
         }
-        
-        private isOutOfRange(key: number) {
-            if (key > this.elements.length - 1) {
-                throw new Error('Out of array range');
-            }
-        }
     }
     ```