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

var Foo=function(s){
    var hidden
    this.setName=function(name){theName=name}
    this.toString=function(){return theName}
    this.public=s
}
var X=new Foo('The X')
X.setName('This is X')
X // returns 'This is X'
X.public // returns 'The X'
X.hidden // returns 'undefined'