requestAnimationFrame polyfill

rAF.js

// requestAnimationFrame polyfill by Erik Möller
// Fixes from Paul Irish and Tino Zijdel
// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
// http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating
(function (w) {
	"use strict";

	var lastTime = 0,
		vendors = ["ms", "moz", "webkit", "o"],
		len = vendors.length,
		x = 0,
		v;

	for (x; x < len && !w.requestAnimationFrame; x += 1) {
		v = vendors[x];
		w.requestAnimationFrame = w[v + "RequestAnimationFrame"];
		w.cancelAnimationFrame = w[v + "CancelAnimationFrame"] || w[v + "CancelRequestAnimationFrame"];
	}

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

			lastTime = currTime + timeToCall;

			return id;
		};
	}

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

}(this));