design a HashMap for js

<script language="javascript"> 

 function HashMap(){ 

 /**Map大小**/ 

 var size=0; 

 /**对象**/ 

 var entry=new Object(); 

 /**Map的存put方法**/ 

 this.put=function(key,value){ 

 if(!this.containsKey(key)){ 

 size++; 

 entry[key]=value; 

 } 

 } 

 /**Map取get方法**/ 

 this.get=function(key){ 

 return this.containsKey(key) ? entry[key] : null; 

 } 

 /**Map删除remove方法**/ 

 this.remove=function(key){ 

 if(this.containsKey(key) && ( delete entry[key] )){ 

 size--; 

 } 

 } 

 /**是否包含Key**/ 

 this.containsKey= function (key){ 

 return (key in entry); 

 } 

 /**是否包含Value**/ 

 this.containsValue=function(value){ 

 for(var prop in entry) 

 { 

 if(entry[prop]==value){ 

 return true; 

 } 

 } 

 return false; 

 } 

 /**所有的Value**/ 

 this.values=function(){ 

 var values=new Array(); 

 for(var prop in entry) 

 { 

 values.push(entry[prop]); 

 } 

 return values; 

 } 

 /**所有的 Key**/ 

 this.keys=function(){ 

 var keys=new Array(); 

 for(var prop in entry) 

 { 

 keys.push(prop); 

 } 

 return keys; 

 } 

 /**Map size**/ 

 this.size=function(){ 

 return size; 

 } 

 /**清空Map**/ 

 this.clear=function(){ 

 size=0; 

 entry=new Object(); 

 } 


 } 

 //创建HashMap对象 

 var hashMap=new HashMap(); 

   hashMap.put("A","1"); 

   hashMap.put("B","2"); 

   hashMap.put("A","5"); 

   hashMap.put("C","3"); 

   hashMap.put("A","4"); 

 alert(hashMap.size()); 


 </script>