simple Object.observe() - run in Chrome Canary with experimental javascript flag enabled.

gistfile1.js

function ObserveMe() { 
  var x = 
	{
		"thing": 
		{ "label": "party", 
		  "value": "republican"
		} 
	} 
	return x;
}

function observer(changes) {
	console.log('changes: ' + JSON.stringify(changes));
}

------------------- in chrome dev tools console -----------------------
var x = ObserveMe();
Object.observe(x, observer);
Object {thing: Object}
x.a = "new thing";
changes: [{"type":"new","object":{"thing":{"label":"party","value":"republican"},"a":"new thing"},"name":"a"}]
"new thing"