function hashtable(){
       this.items = {}
}
var ht = new hashtable();
hashtable.prototype.Add = function(key,value) {
      if (typeof(key) == "undefined")
            return;
      if (ht.Contains(key)==true)
            return;
      if (typeof(value)=="undefined")
            return
      this.items[key] = value;
}

hashtable.prototype.Contains = function (key) {
        return typeof(this.items[key])!="undefined";
}

hashtable.prototype.Remove = function(key){
       delete this.items[key];
}

hashtable.prototype.Count = function (){
    var i=0;
    for (var k in this.items) i++;
    return i;
}

hashtable.prototype.item = function (key) {
       return this.items[key];
}

hashtable.prototype.Clear = function() {
      for (var k in this.items)
            delete this.items[k];
}