JavaScript之HashTable

<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd" >
< html >
     < head >
         < meta  http-equiv ="Content-Type"  content ="text/html; charset=gb2312"   />
         < title > JSHashTable </ title >
         < script  type =text/javascript >
             function  HashTable()
            {
                 this .__hash  =  {};
                 this .Add  =   function (key,value)
                {
                     if ( typeof (key)  !=   " undefined " )
                    {
                         // if it not contains in hashtable 
                         if ( !   this .contains(key))
                        {
                             this .__hash[key]  =   typeof (value)  ==   " undefined "   ?   null  : value;
                             return   true ;
                        }
                         else {
                             return   false ;
                        }
                    }
                };    
                
                 this .Remove  =   function (key){
                     delete   this .__hash[key];
                };        
                 this .count  =   function (){
                     var  i  =   0 ;
                     for ( var  obj  in   this .__hash)
                    {
                        i ++ ;
                    }
                     return  i;
                };    
                 this .items  =   function (key){
                     return   this .__hash[key];
                };
                 this .contains  =   function (key){
                     return   typeof ( this .__hash[key])  !=   " undefined " ;
                };
                 this .clear  =   function (){
                     for ( var  obj  in   this .__hash)
                    {
                         delete   this .__hash[k];
                    }
                };
            }
            
             var  obj  =   new  HashTable();
            obj.Add( " a " );
            obj.Add( " b " , " b " );
            obj.Add( " a " );
            obj.Remove( " a " );
            alert(obj.contains( " a " ));
            obj.Add( " c " , " I love you " );
            alert(obj.items( " c " ));
         </ script >
     </ head >
     < body >
     </ body >
</ html >