function wheel()

in Documents/assets/smoothscroll/smooth-scroll.js [292:370]
53 lines of code
29 McCabe index (conditional complexity)

function wheel(event) {

    if (!initDone) {
        init();
    }

    var target = event.target;

    // leave early if default action is prevented
    // or it's a zooming event with CTRL
    if (event.defaultPrevented || event.ctrlKey) {
        return true;
    }

    // leave embedded content alone (flash & pdf)
    if (isNodeName(activeElement, 'embed') ||
       (isNodeName(target, 'embed') && /\.pdf/i.test(target.src)) ||
        isNodeName(activeElement, 'object') ||
        target.shadowRoot) {
        return true;
    }

    var deltaX = -event.wheelDeltaX || event.deltaX || 0;
    var deltaY = -event.wheelDeltaY || event.deltaY || 0;

    if (isMac) {
        if (event.wheelDeltaX && isDivisible(event.wheelDeltaX, 120)) {
            deltaX = -120 * (event.wheelDeltaX / Math.abs(event.wheelDeltaX));
        }
        if (event.wheelDeltaY && isDivisible(event.wheelDeltaY, 120)) {
            deltaY = -120 * (event.wheelDeltaY / Math.abs(event.wheelDeltaY));
        }
    }

    // use wheelDelta if deltaX/Y is not available
    if (!deltaX && !deltaY) {
        deltaY = -event.wheelDelta || 0;
    }

    // line based scrolling (Firefox mostly)
    if (event.deltaMode === 1) {
        deltaX *= 40;
        deltaY *= 40;
    }

    var overflowing = overflowingAncestor(target);

    // nothing to do if there's no element that's scrollable
    if (!overflowing) {
        // except Chrome iframes seem to eat wheel events, which we need to
        // propagate up, if the iframe has nothing overflowing to scroll
        if (isFrame && isChrome)  {
            // change target to iframe element itself for the parent frame
            Object.defineProperty(event, "target", {value: window.frameElement});
            event = new event.constructor(event.type, event); // redefine event because already dispatched
            return parent.dispatchEvent(event);
        }
        return true;
    }

    // check if it's a touchpad scroll that should be ignored
    if (!options.touchpadSupport && isTouchpad(deltaY)) {
        return true;
    }

    // scale by step size
    // delta is 120 most of the time
    // synaptics seems to send 1 sometimes
    if (Math.abs(deltaX) > 1.2) {
        deltaX *= options.stepSize / 120;
    }
    if (Math.abs(deltaY) > 1.2) {
        deltaY *= options.stepSize / 120;
    }

    scrollArray(overflowing, deltaX, deltaY);
    event.preventDefault();
    scheduleClearCache();
}