requestAnimationFrame polyfill

rAF.js

// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
// http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating

// requestAnimationFrame polyfill by Erik Möller
// fixes from Paul Irish and Tino Zijdel and Julien Cayzac

(function() {
	var lastTime = 0,
		vendors = ['ms', 'moz', 'webkit', 'o'],
		x,
		ok = function() { return window.requestAnimationFrame && window.cancelAnimationFrame }
	for (x in vendors) {
		window.requestAnimationFrame = w[vendors[x]+'RequestAnimationFrame']
		window.cancelAnimationFrame = w[vendors[x]+'CancelAnimationFrame'] || w[vendors[x]+'CancelRequestAnimationFrame']
		if (ok()) return
	}

	window.requestAnimationFrame = function(callback, ignored) {
		var currTime = new Date().getTime(),
			timeToCall = Math.max(1, 16 - (currTime - lastTime)),
			id = window.setTimeout(function() { callback(currTime + timeToCall); }, timeToCall)
		lastTime = currTime + timeToCall
		return id
	}

	window.cancelAnimationFrame = function(id) { clearTimeout(id) }
}())