Js 封装HashMap

/**
* @author TanDong
*/
function HashMap()
{
     var size = 0;
     var entry = new Object();
    
     this.put = function (key , value)
     {
         if(!this.containsKey(key))
         {
             size ++ ;
         }
         entry[key] = value;
     }
    
     this.get = function (key)
     {
         return this.containsKey(key) ? entry[key] : null;
     }
    
     this.remove = function ( key )
     {
         if( this.containsKey(key) && ( delete entry[key] ) )
         {
             size --;
         }
     }
    
     this.containsKey = function ( key )
     {
         return (key in entry);
     }
    
     this.containsValue = function ( value )
     {
         for(var prop in entry)
         {
             if(entry[prop] == value)
             {
                 return true;
             }
         }
         return false;
     }
    
     this.values = function ()
     {
         var values = new Array();
         for(var prop in entry)
         {
             values.push(entry[prop]);
         }
         return values;
     }
    
     this.keys = function ()
     {
         var keys = new Array();
         for(var prop in entry)
         {
             keys.push(prop);
         }
         return keys;
     }
    
     this.size = function ()
     {
         return size;
     }
    
     this.clear = function ()
     {
         size = 0;
         entry = new Object();
     }
}