Try to resize your browser. This block should change it's color on every resize event. Now look at the JS tab. See? Now <div> and others have 'onresize' event even without timer! ;D You can resize this block in dev tools to test more advanced scenarios.
It is tiny (about 800 bytes min + gzip) and dependency free.
Works just everywhere:
Chrome 1+
Firefox 1+
IE 4+
Safari 1+
Opera 4+
repo on github
with ♥ by LegoMushroom