Javascript 实现Hashtable

//javascript Hashtable 实现
var Hashtable=function()...{
    this.Clear();
}
Hashtable.prototype=...{
    Add:    function(key,value)...{    //实现Add 方法
                if(!key) return;
                if(typeof(value) === 'undefined') return;
                this.Items[key] = value;
                this.Count++;
            },
    Clear:    function()...{                //实现Clear 方法
                this.Items=null;
                this.Items=new Object();
            },
    ContainsKey:function(key)...{        //实现ContainsKey,检测表中是否包含特定的键
                if(!key)return false;
                if(typeof(this.Items[key])=='undefined')
                    return false;
                return true;
            },
    ContainsValue:function(value)...{    //实现ContainsValue,检测表中是否包含特定的值
                if(!value)return false;
                for (var key in this.Items)...{
                   if(this.Items[key]==value)
                        return true;
                }
                return false;
            },
    Count:    0,        //键或值总数
    GetValue:function(key)...{    //实现GetValue方法,通过键值获取value;                
                if(!this.ContainsKey(key))return null;
                return this.Items[key];
            },
    GetValueAt:function(index)...{    //实现GetValueAt方法,通过索引值获取value;
                if(isNaN(index)) return null;
                if(index<0 || index>this.Count)return null;
                var i=0;
                for(var key in this.Items)...{
                    if(i == index)return this.Items[key];
                    i++;
                }
                return null;
            },
    Keys:    function()...{  //实现Keys方法,获取hash表的所有key 返回Array
                var arr=new Array();
                for(var key in this.Items)
                    arr.push(key);
                return arr;
            },
    Remove:    function(key)...{    //实现Remove方法,删除某个特定的键
                if(!key)return;
                delete this.Items[key];
                this.Count--;
                return;
            },
    RemoveAt:function(index)...{    //实现Remove方法,删除某个特定的索引值
                if(isNaN(index)) return null;
                if(index<0 || index>this.Count)return null;
                var i=0;
                for(var key in this.Items)...{
                    if(i == index)...{this.Remove(key);return;}
                    i++;
                }
                return null;
            },
    RemoveRange:function(startindex,endindex)...{    //RemoveRange 删除索引值在某个范围的值
                if(isNaN(startindex) || isNaN(endindex)) return null;
                if(startindex<0)startindex=0;
                if(endindex>this.Count-1)endindex=this.Count-1;
                for(var i=startindex;i<this.Count;i++)
                    this.RemoveAt(i);
            },
    Values:function()...{    //实现Values方法,获取hash表的所有键的值 返回Array
                var arr=new Array();
                for(var key in this.Items)
                    arr.push(this.Items[key]);
                return arr;
            }
    }

//测试hashtable
function testhash()...{
    var ht=new Hashtable();
    ht.Add('a',2);
    ht.Add('b',4);
    ht.Add(1,5);
    alert(ht.Count);
    ht.RemoveAt(2);
    alert(ht.Count);
    alert(ht.Items[1]);
    alert(ht.GetValueAt(0));
}

 

修正: 

Add: function(key,value){ //实现Add 方法
    if(!key) return;
    if(typeof(value) === 'undefined') return;
    if(!this.ContainsKey(key))this.Count++;   /*修正Add时Count计数不准确*/
    this.Items[key] = value;
   },