Get notified when added new property to window object - js

Question

I need to listen to some event (if it exists of course) to know when new property was added to window object. Is that possible?

For example:

I have a code in application that don't know what global variable some library exposes (eg underscore.js which exposes global _ instead of underscore ). I need to be notified that new property was assigned to window .

Answer 1

There are two ways you could try to do that but neither is a great option.

1. You can check for changes to the window object using setInterval . This will be slow and there will be a delay between when a new property is added to window and when your code will notice it. Here is some code that shows one way of doing that: http://jsbin.com/vubew/1/edit?js,console

    (function(){ 'use strict'; var keys = Object.keys(window).join(); setInterval(function(){ var newKeys = Object.keys(window).join(); if (newKeys !== keys) { console.log('`window` changed'); keys = newKeys; } }, 100); })(); 

2. You could use ES7's Object.observe method. Unfortunately, only Chrome supports it (behind an experimental flag) right now.

Once you determine there has been a change with one of these methods you'd generate an event that your code would be listening for.