top.js

function goTop(acceleration, time)
{
        acceleration = acceleration || 0.1;
        time = time || 16;

        var x1 = 0;
        var y1 = 0;
        var x2 = 0;
        var y2 = 0;
        var x3 = 0;
        var y3 = 0;

        if (document.documentElement)
        {
                x1 = document.documentElement.scrollLeft || 0;
                y1 = document.documentElement.scrollTop || 0;
        }
        if (document.body)
        {
                x2 = document.body.scrollLeft || 0;
                y2 = document.body.scrollTop || 0;
        }
        var x3 = window.scrollX || 0;
        var y3 = window.scrollY || 0;

        var x = Math.max(x1, Math.max(x2, x3));
        var y = Math.max(y1, Math.max(y2, y3));

        var speed = 1 + acceleration;
        window.scrollTo(Math.floor(x / speed), Math.floor(y / speed));

        if(x > 0 || y > 0)
        {
                var invokeFunction = "goTop(" + acceleration + ", " + time + ")";
                window.setTimeout(invokeFunction, time);
        }
}