Object.watch() for all browsers?

Question

Please note that Object.Watch and Object.Observe are both deprecated now (as of Jun 2018).

---

I was looking for an easy way to monitor an object

Answer 1

The answers to this question are a bit outdated. Object.watch and Object.observe are both deprecated and should not be used.

Today, you can now use the Proxy object to monitor (and intercept) changes made to an object. Here's a basic example:

var targetObj = {};
var targetProxy = new Proxy(targetObj, {
  set: function (target, key, value) {
      console.log(`${key} set to ${value}`);
      target[key] = value;
  }
});

targetProxy.hello_world = "test"; // console: 'hello_world set to test'

If you need to observe changes made to a nested object, then you need to use a specialized library. I published Observable Slim and it works like this:

var test = {testing:{}};
var p = ObservableSlim.create(test, true, function(changes) {
    console.log(JSON.stringify(changes));
});

p.testing.blah = 42; // console:  [{"type":"add","target":{"blah":42},"property":"blah","newValue":42,"currentPath":"testing.blah",jsonPointer:"/testing/blah","proxy":{"blah":42}}]