Javascript: 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
(function () {
	var lastTime = 0;
	var vendors = ['ms', 'moz', 'webkit', 'o'];
	for (var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) {
		window.requestAnimationFrame = window[vendors[x] + 'RequestAnimationFrame'];
		window.cancelAnimationFrame = window[vendors[x] + 'CancelAnimationFrame'] || window[vendors[x] + 'CancelRequestAnimationFrame'];
	}

	if (!window.requestAnimationFrame) window.requestAnimationFrame = function (callback, element) {
		var currTime = new Date().getTime();
		var timeToCall = Math.max(0, 16 - (currTime - lastTime));
		var id = window.setTimeout(function () {
			callback(currTime + timeToCall);
		}, timeToCall);
		lastTime = currTime + timeToCall;
		return id;
	};

	if (!window.cancelAnimationFrame) window.cancelAnimationFrame = function (id) {
		clearTimeout(id);
	};
}());