Cross Browser JavaScript Scroll to Top

by Taufik Nurrohman

HTML

<p>Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long page. Very long...

CSS

html,body {
    height:100%;
    min-height:100%;
    margin:0;
    padding:0;
}

body {overflow:auto}

JavaScript

function scrollTo(element, to, duration) {

    // http://robertpenner.com/easing/
    // t = current time, b = start value, c = change in value, d = duration
    Math.easeInOutQuad = function(t, b, c, d) {
        t /= d / 2;
        if (t < 1) return c / 2 * t * t + b;
        t--;
        return -c / 2 * (t * (t - 2) - 1) + b;
    };

    var start = element.scrollTop,
        change = to - start,
        currentTime = 0,
        increment = 20,
        animateScroll = function() {
        currentTime += increment;
        var val = Math.easeInOutQuad(currentTime, start, change, duration);
        element.scrollTop = val;
        if (currentTime < duration) {
            setTimeout(animateScroll, increment);
        }
    }; animateScroll();

}

document.getElementsByTagName('button')[0].onclick = function() {
    scrollTo(document.documentElement, 0, 1000);
    scrollTo(document.body, 0, 1000);
};