模拟一个HashTable类，包含有add、remove、contains、length方法

[size=medium]如题，求教：模拟一个HashTable类，包含add、remove、contains、length方法？[/size]

[quote]
[code="js"]
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 + "}";
        };
    }

[/code]
[/quote]

[code="js"]
/* 自定义JavaScript Map实现 */
function Map() {

var struct = function(key, value) {

this.key = key;

this.value = value;

};

var put = function(key, value){  
    for (var i = 0; i < this.arr.length; i++) {  
        if ( this.arr[i].key === key ) { 
            this.arr[i].value = value;    
            return;    
        }    
    }    
    this.arr[this.arr.length] = new struct(key, value);    
};

var get = function(key) {    
    for (var i = 0; i < this.arr.length; i++) {    
        if ( this.arr[i].key === key ) {    
            return this.arr[i].value;    
        }    
    }    
    return null;    
};

var remove = function(key) {    
    var v;    
    for (var i = 0; i < this.arr.length; i++) {    
        v = this.arr.pop();    
        if ( v.key === key ) {    
            continue;    
        }    
        this.arr.unshift(v);    
    }    
};

var size = function() {    
    return this.arr.length;    
};

var isEmpty = function() {    
    return this.arr.length <= 0;    
};

this.arr = new Array();    
this.get = get;    
this.put = put;    
this.remove = remove;    
this.size = size;    
this.isEmpty = isEmpty;

}

[/code]