Is it possible to create a hidden property in javascript

Question

I want to create an object with a hidden property(a property that does not show up in a for (var x in obj loop). Is it possible to do this?

Answer 1

It's a bit tricky!

function secret() {
  var cache = {};
  return function(){
    if (arguments.length == 1) { return cache[arguments[0]];}
    if (arguments.length == 2) { cache[arguments[0]] = arguments[1]; }
  };
}
var a = secret();

a.hello = 'world';
a('hidden', 'from the world');

If you are a real pro though, you can do it this way!

var a = new (secret())();

a.hello = 'world';
a.constructor('hidden', 'from the world');

Now if you look a in firebug it will be an object ... but you know better! ;-)