window.requestAnimationFrame polyfill (with high resolution timing, very precise)

requestAnimationFrame-polyfill.js

'use strict';

// requestAnimationFrame polyfill by Erik Möller.
// Fixes from Paul Irish, Tino Zijdel, Andrew Mao, Klemen Slavic, Darius Bacon and Joan Alba Maldonado.
// Adapted from https://gist.github.com/paulirish/1579671 which derived from
// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
// http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating
// Added high resolution timing. This window.performance.now() polyfill can be used: https://gist.github.com/jalbam/cc805ac3cfe14004ecdf323159ecf40e
// MIT license
// Gist: https://gist.github.com/jalbam/5fe05443270fa6d8136238ec72accbc0
(function() {
	var vendors = ['webkit', 'moz', 'ms', 'o'], vp = null;
	for (var x = 0; x < vendors.length && !window.requestAnimationFrame && !window.cancelAnimationFrame; x++)
	{
		vp = vendors[x];
		window.requestAnimationFrame = window.requestAnimationFrame || window[vp + 'RequestAnimationFrame'];
		window.cancelAnimationFrame = window.cancelAnimationFrame || window[vp + 'CancelAnimationFrame'] || window[vp + 'CancelRequestAnimationFrame'];
	}
	if (/iP(ad|hone|od).*OS 6/.test(window.navigator.userAgent) || !window.requestAnimationFrame || !window.cancelAnimationFrame) //iOS6 is buggy.
	{
		var lastTime = 0;
		window.requestAnimationFrame = function(callback, element)
		{
			var now = window.performance.now();
			var nextTime = Math.max(lastTime + 16, now); //First time will execute it immediately but barely noticeable and performance is gained.
			return setTimeout(function() { callback(lastTime = nextTime); }, nextTime - now);
		};
		window.cancelAnimationFrame = clearTimeout;
	}
}());