Another Game Loop

ChronoTron.js

function ChronoTron(conf) {
	function gots (name, type) {
		return (
			(type === 'Array') ? 
				conf[name] instanceof Array :
				conf[name] && typeof conf[name] === type
		);
	}
	switch (true) {
		case typeof conf !== 'object':
			throw "gimme object";
		case !gots('update', 'function'):
			throw "need function member called 'update'";
		case !gots('draw', 'function'):
			throw "need function member called 'draw'";
		case !gots('fps', 'number'):
			throw "need number member called 'fps'";
	}
	for(i in conf) { this[i] = conf[i]; }

	this.mspf  = (1000 / this.fps)|0; // slightly more aggressive
	this.stuff = {}; // don't garbage collect me bro
}
ChronoTron.prototype.reqAnimFrame = (function () {
	return (
		window.requestAnimationFrame         || 
		window.mozRequestAnimationFrame      ||
		window.webkitRequestAnimationFrame   || 
		window.oRequestAnimationFrame        ||
		function (cb) { setTimeout(cb, 0); }
	).bind(window);
})();
ChronoTron.prototype.__update = function (n) {
	for (; n--; n > 0) { this.update(); }
};
ChronoTron.prototype.__cycle = function () {
	this.__update((((new Date().getTime()) - this.stuff.last)/this.mspf)|0);
	this.reqAnimFrame(this.draw);
	this.stuff.last = new Date().getTime();
	!this.pause && setTimeout(this.__cycle.bind(this), this.mspf);
};
ChronoTron.prototype.start = function () {
	this.pause = false;
	this.stuff.last = new Date().getTime();
	this.__cycle();
};
ChronoTron.prototype.stop = function () {
	this.pause = true;
};