function init()

in Documents/assets/smoothscroll/smooth-scroll.js [81:159]
34 lines of code
10 McCabe index (conditional complexity)

function init() {

    if (initDone || !document.body) return;

    initDone = true;

    var body = document.body;
    var html = document.documentElement;
    var windowHeight = window.innerHeight;
    var scrollHeight = body.scrollHeight;

    // check compat mode for root element
    root = (document.compatMode.indexOf('CSS') >= 0) ? html : body;
    activeElement = body;

    initTest();

    // Checks if this script is running in a frame
    if (top != self) {
        isFrame = true;
    }

    /**
     * Safari 10 fixed it, Chrome fixed it in v45:
     * This fixes a bug where the areas left and right to
     * the content does not trigger the onmousewheel event
     * on some pages. e.g.: html, body { height: 100% }
     */
    else if (isOldSafari &&
             scrollHeight > windowHeight &&
            (body.offsetHeight <= windowHeight ||
             html.offsetHeight <= windowHeight)) {

        var fullPageElem = document.createElement('div');
        fullPageElem.style.cssText = 'position:absolute; z-index:-10000; ' +
                                     'top:0; left:0; right:0; height:' +
                                      root.scrollHeight + 'px';
        document.body.appendChild(fullPageElem);

        // DOM changed (throttled) to fix height
        var pendingRefresh;
        refreshSize = function () {
            if (pendingRefresh) return; // could also be: clearTimeout(pendingRefresh);
            pendingRefresh = setTimeout(function () {
                if (isExcluded) return; // could be running after cleanup
                fullPageElem.style.height = '0';
                fullPageElem.style.height = root.scrollHeight + 'px';
                pendingRefresh = null;
            }, 500); // act rarely to stay fast
        };

        setTimeout(refreshSize, 10);

        addEvent('resize', refreshSize);

        // TODO: attributeFilter?
        var config = {
            attributes: true,
            childList: true,
            characterData: false
            // subtree: true
        };

        observer = new MutationObserver(refreshSize);
        observer.observe(body, config);

        if (root.offsetHeight <= windowHeight) {
            var clearfix = document.createElement('div');
            clearfix.style.clear = 'both';
            body.appendChild(clearfix);
        }
    }

    // disable fixed background
    if (!options.fixedBackground && !isExcluded) {
        body.style.backgroundAttachment = 'scroll';
        html.style.backgroundAttachment = 'scroll';
    }
}