So lets say I've added some prototype methods to the Array class:

Array.prototype.containsKey = function(obj) {

    for(var key in this)

        if (key == obj) return true;

    return false;

}



Array.prototype.containsValue = function(obj) {

    for(var key in this)

        if (this[key] == obj) return true;

    return false;

}

then I create an associative array and attempt to loop through it's keys:

var arr = new Array();

arr['One'] = 1;

arr['Two'] = 2;

arr['Three'] = 3;



for(var key in arr)

   alert(key);

this returns five items:

  -One

  -Two

  -Three

  -containsKey

  -containsValue

but I want (expect?) only three. Am I approaching this wrong? is there a way to hide the prototype methods? or should I be doing something differently?