tween.js

/*
// Tweener Like snippet
new Tween(div.style,{time:1, onComplete:function(){},left:{to:0,from:100,tmpl:"+$#px"}});
// @require http://gist.github.com/13572.txt
*/
function Tween(item, opt) {
	var self = this, TIME = 10, time = (opt.time||1) * 1000, TM_EXP = /(\+)?\$([\#\d])/g, sets = [],
		easing = opt.transition || function(t, b, c, d){return c*t/d + b;}, _T = {time:1,onComplete:1,transition:1,delay:1};
	for (var k in opt) if (!_T[k]) {
		var set = opt[k], from = set.from || parseFloat(item[k]) || 0, values = [], tmpl = set.tmpl || '$#';
		sets.push({key:k, from:from, to:set.to, tmpl:tmpl});
	}
	var L = sets.length, delay = opt.delay*1000 || 0, startTime = new Date()*1 + delay, endTime = time + startTime, dist = endTime - startTime, run = function(){
		var now = new Date()*1, tim = now - startTime;
		for (var k = 0; k < L; ++k) {
			var set = sets[k], val = easing(tim, set.from, set.to - set.from, dist);
			item[set.key] = set.tmpl.replace(TM_EXP, function(m, p, m1){return p && val < 0 ? 0 : (m1 == '#' ? val : val.toFixed(m1));});
		}
		if (tim <= dist) {setTimeout(function(){run.call(self);},TIME);}
		else {
			for (var k = 0; k < L; ++k) {item[sets[k].key] = sets[k].tmpl.replace(TM_EXP, sets[k].to);}
			if (typeof opt.onComplete == 'function') opt.onComplete(item);
		}
	};
	delay ? setTimeout(function(){run();},delay) : run(0);
}