Adds class to bookmark/local links when the linked element is in view.

jquery.scroll-highlight.js

/*!
 * Adds class to bookmark/local links when the linked element is in view.
 *
 * Requires https://gist.github.com/jbuncle/6f6185e88be875b2585e736a422c3f15 for detecting when element is in view.
 *
 * Copyright 2016 James Buncle
 * 
 * Released under the MIT license.
 * http://jquery.org/license
 *
 */
(function ($) {
    $.fn.scrollHighlight = function (className) {
        return this.filter('[href^="#"]').each(function () {
            var $link = $(this);
            var target = $link.attr('href').replace(/("|'|&|:|\.|\[|\]|,|\(|\)|\/|\?)/g, "\\$1");
            var $for = $(target);
            $(window).scroll(function () {
                if ($for.inViewport()) {
                    $link.addClass(className);
                } else {
                    $link.removeClass(className);
                }
            });
        });
    };
})(jQuery);