Track whether object changed

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

Javascript does not allow you to set programmatic watchpoints/events on arbitrary objects/variables.

You can use encapsulation to hide individual values inside the object from the outside world, allowing them to be modified only through dedicated "setter" functions that have the side-effects you desire.