Super-duper-lightweight tweening "library"

tween.js

//Super-duper-lightweight tweening "library".
//An actual library like https://github.com/tweenjs/tween.js would probably be better..
function TWEEN(from, to, duration, callback, easing) {
    //ease-out quad: https://github.com/tweenjs/tween.js/blob/master/src/Tween.js#L544
    easing = easing || function(t) { return t * (2 - t); };

    var diff = to - from,
        startTime;

    function anim(time) {
        var prog, val;

        if(!startTime) {
            startTime = time;
            prog = 0;
            val = from;
        }
        else {
            prog = (time - startTime) / duration;
            val = (prog < 1) ? from + (diff * easing(prog)) : to;
        }
        callback(val);

        if(prog < 1) {
            requestAnimationFrame(anim);
        }
    }
    requestAnimationFrame(anim);
}

tween.min.js

function TWEEN(b,e,h,k,c){function f(a){if(d){a=(a-d)/h;var g=1>a?b+l*c(a):e}else d=a,a=0,g=b;k(g);1>a&&requestAnimationFrame(f)}c=c||function(a){return a*(2-a)};var l=e-b,d;requestAnimationFrame(f)};