Which browsers, if any, support Object.observe? I'm surprised I'm unable to find any info on this.
(And are you aware about any estimated times of arrival for this feature?)
About Object.observe: "Object.observe allows for the direct observation of changes to ECMAScript objects. It allows an observer to receive a time-ordered sequence of change records which describe the set of changes which took place to the set of observed objects." — see ecmascript.org, the Solution section.)
Edit November 2015: Apparently Object.observe has been cancelled:
http://www.infoq.com/news/2015/11/object-observe-withdrawn
https://esdiscuss.org/topic/an-update-on-object-observe
"I plan to withdraw the Object.observe proposal from TC39"
https://esdiscuss.org/topic/save-object-observe-please-make-weakmap-weakset-observable
"Save Object.observe()! (please)"
No browsers. If its not true today, it will be true someday, and then this can be the accepted answer.