js自定义Map

<script type="text/javascript">
/**
* 自定义Map对象
*/
 function Map(){
 	 this.keys = new Array();
 	 this.data = new Array();
 	
 	 
 	 this.put = function(key,value){
 	  if(this.data[key] == null){
 	   this.keys.push(value);
 	  }
 	  this.data[key] = value;
 	 };
 	
 	 
 	 this.get = function(key){
 	  return this.data[key];
 	 };
 	
 	 
 	 this.remove = function(key){
 	  this.keys.remove(key);
 	  this.data[key] = null;
 	 };
 	
 	 
 	 this.isEmpty = function(){
 	  return this.keys.length == 0;
 	 };
 	
 	 
 	 this.size = function(){
 	  return this.keys.length;
 	 };
 }
</script>