diff --git a/problems/0242.有效的字母异位词.md b/problems/0242.有效的字母异位词.md
index 1006ea35..ba802bbd 100644
--- a/problems/0242.有效的字母异位词.md
+++ b/problems/0242.有效的字母异位词.md
@@ -205,6 +205,19 @@ var isAnagram = function(s, t) {
     }
     return true;
 };
+
+var isAnagram = function(s, t) {
+  if(s.length !== t.length) return false;
+  let char_count = new Map();
+  for(let item of s) {
+    char_count.set(item, (char_count.get(item) || 0) + 1) ;
+  }
+  for(let item of t) {
+    if(!char_count.get(item)) return false;
+    char_count.set(item, char_count.get(item)-1);
+  }
+  return true;
+};
 ```
 
 TypeScript：