watcher

Object Property Change Notifications

Watches an object path for changes, notifies in the style of Object.watch(), but handles all browsers using Object.observe, Object.watch, Object.defineProperty, and (as a last-resort) polling.

Usage

watcher(
  window.myClass.myObject, 	// path
  "myProperty", 		// key to watch
  function(key, value, was){ 	// callback function
       alert( key+" changed from " + was + " to " + value ); 
});

Using the tee function to subscribe two paths

No callback, just push a value from one object to another, in this case an object prop to the page title:

 watcher.tee( 
     "window.myClass.myObject.myProperty", 	// path to watch
     "document.title", 				// path to push values to
 );

That All Folks!