JavaScript Hashtable

function Hashtable()
{
    this._hash        = new Object();
            = function(key,value){
                        if(typeof(key)!="undefined"){
                            if((key)==false){
                                this._hash[key]=typeof(value)=="undefined"?null:value;
                                return true;
                            } else {
                                return false;
                            }
                        } else {
                            return false;
                        }
                    }
            = function(key){delete this._hash[key];}
            = function(){var i=0;for(var k in this._hash){i++;} return i;}
            = function(key){return this._hash[key];}
        = function(key){ return typeof(this._hash[key])!="undefined";}
            = function(){for(var k in this._hash){delete this._hash[k];}}

} 

var a = new Hashtable();

("aa");
("bb",2342);
("bb",2342);

("aa");

alert(());

alert(("bb"));

alert(("aa"));

alert(("bb"));