I just made a pure Javascript function based on that code. Javascript only version demo: http://jsbin.com/copidifiji
That is the independent code from jQuery
if (window.addEventListener) {window.addEventListener('DOMMouseScroll', wheel, false);
window.onmousewheel = document.onmousewheel = wheel;}
function wheel(event) {
var delta = 0;
if (event.wheelDelta) delta = (event.wheelDelta)/120 ;
else if (event.detail) delta = -(event.detail)/3;
handle(delta);
if (event.preventDefault) event.preventDefault();
event.returnValue = false;
}
function handle(sentido) {
var inicial = document.body.scrollTop;
var time = 1000;
var distance = 200;
animate({
delay: 0,
duration: time,
delta: function(p) {return p;},
step: function(delta) {
window.scrollTo(0, inicial-distance*delta*sentido);
}});}
function animate(opts) {
var start = new Date();
var id = setInterval(function() {
var timePassed = new Date() - start;
var progress = (timePassed / opts.duration);
if (progress > 1) {progress = 1;}
var delta = opts.delta(progress);
opts.step(delta);
if (progress == 1) {clearInterval(id);}}, opts.delay || 10);
}