function scrollArray()

in Documents/assets/smoothscroll/smooth-scroll.js [185:281]

• 29 lines of code
• 7 McCabe index (conditional complexity)

function scrollArray(elem, left, top) {

    directionCheck(left, top);

    if (options.accelerationMax != 1) {
        var now = Date.now();
        var elapsed = now - lastScroll;
        if (elapsed < options.accelerationDelta) {
            var factor = (1 + (50 / elapsed)) / 2;
            if (factor > 1) {
                factor = Math.min(factor, options.accelerationMax);
                left *= factor;
                top  *= factor;
            }
        }
        lastScroll = Date.now();
    }

    // push a scroll command
    que.push({
        x: left,
        y: top,
        lastX: (left < 0) ? 0.99 : -0.99,
        lastY: (top  < 0) ? 0.99 : -0.99,
        start: Date.now()
    });

    // don't act if there's a pending queue
    if (pending) {
        return;
    }

    var scrollWindow = (elem === document.body);

    var step = function (time) {

        var now = Date.now();
        var scrollX = 0;
        var scrollY = 0;

        for (var i = 0; i < que.length; i++) {

            var item = que[i];
            var elapsed  = now - item.start;
            var finished = (elapsed >= options.animationTime);

            // scroll position: [0, 1]
            var position = (finished) ? 1 : elapsed / options.animationTime;

            // easing [optional]
            if (options.pulseAlgorithm) {
                position = pulse(position);
            }

            // only need the difference
            var x = (item.x * position - item.lastX) >> 0;
            var y = (item.y * position - item.lastY) >> 0;

            // add this to the total scrolling
            scrollX += x;
            scrollY += y;

            // update last values
            item.lastX += x;
            item.lastY += y;

            // delete and step back if it's over
            if (finished) {
                que.splice(i, 1); i--;
            }
        }

        // scroll left and top
        if (scrollWindow) {
            window.scrollBy(scrollX, scrollY);
        }
        else {
            if (scrollX) elem.scrollLeft += scrollX;
            if (scrollY) elem.scrollTop  += scrollY;
        }

        // clean up if there's nothing left to do
        if (!left && !top) {
            que = [];
        }

        if (que.length) {
            requestFrame(step, elem, (1000 / options.frameRate + 1));
        } else {
            pending = false;
        }
    };

    // start a new queue of actions
    requestFrame(step, elem, 0);
    pending = true;
}