js hashTable

function Hashtable() 
        {
            this.container = new Object();
            
            /**//** put element */
            this.put = function (key, value) 
            {
                if (typeof (key) == "undefined")
                {
                    return false;
                } 
                if (this.contains(key))
                {
                    return false;
                } 
                this.container[key] = typeof (value) == "undefined" ? null : value;
                return true;
            };
        
            /**//** remove element */
            this.remove = function (key) 
            {
                delete this.container[key];
            };
            
            /**//** get size */
            this.size = function () 
            {
                var size = 0;
                for (var attr in this.container) 
                {
                    size++;
                }
                return size;
            };
            
            /**//** get value by key */
            this.get = function (key) 
            {
                return this.container[key];
            };
        
            /**//** containts a key */
            this.contains = function (key) 
            {
                return typeof (this.container[key]) != "undefined";
            };
        
            /**//** clear all entrys */
            this.clear = function () 
            {
                for (var attr in this.container)
                {
                    delete this.container[attr];
                }
            };
            
            /**//** hashTable 2 string */
            this.toString = function()
            {
                var str = "";
                for (var attr in this.container)
                {
                    str += "," + attr + "=" + this.container[attr];
                }
                if(str.length>0)
                {
                    str = str.substr(1, str.length);
                }
                return "{" + str + "}";
            };
        }
        
        var hashtable = new Hashtable();
        hashtable.put('1','huyvanpull');
        hashtable.put('2','ensoodge');
        hashtable.put('3','huyfan');
        
        hashtable.remove('2');
        alert(hashtable.toString());