animated scroll to anchor without jquery
function animate(elem, style, unit, from, to, time, prop) {
if (!elem) {
return;
}
var start = new Date().getTime(),
timer = setInterval(function () {
var step = Math.min(1, (new Date().getTime() - start) / time);
if (prop) {
elem[style] = (from + step * (to - from))+unit;
} else {
elem.style[style] = (from + step * (to - from))+unit;
}
if (step === 1) {
clearInterval(timer);
}
}, 25);
if (prop) {
elem[style] = from+unit;
} else {
elem.style[style] = from+unit;
}
}
window.onload = function () {
var target = document.getElementById("div5");
animate(document.scrollingElement || document.documentElement, "scrollTop", "", 0, target.offsetTop, 2000, true);
};