Question

// A simple Javascript Object / String
var object = "hello";

// Imagine a button in the DOM, and if it's clicked the object value will change
document.getElementById("button").onclick = function(){
   window.object = "hello world";
}

// Now I would like to track and do something when the object is changed, ex:
object.onreadystatechange = function(){
   alert(object);
}

Note: This could sound stupid, because I could get the change in the onclick event on the button, but this is not what I want, I want strictly to track the change on the object itself for any kind of use, the above code is is just an example.

Answer 1

Well you can make it an actual oject with get and set methods:

// A simple Javascript Object 
var object = new (function(){
    this.text = 'hello';

    this.setText = function(msg){
         this.text = msg
         //on change event
    }
})();

// Imagine a button in the DOM, and if it's clicked the object value will change
document.getElementById("button").onclick = function(){
   object.setText('New Text');
}

Here is a demo fiddle: http://jsfiddle.net/maniator/BSYpz/