https://www.wunderkarten.de/common/components-js/menu_widget.js?2033fa8d

1$(window).load(function () {
2    if ($(".list-collapsible") && $(".sidebar_widget > p")) {
3        $(".sidebar_widget > p").on("click", function (e) {
4            //Prevent click from following a link
5            e.preventDefault();
6            //Check if the widget should be collapsed or not
7            if ($(this).parent().find(".list-collapsible").length) {
8                //Add or remove class collapsed
9                $(this).toggleClass("is_collapsed");
10                //Collapse the widget
11                var widget = $(this)[0].nextElementSibling;
12                $(widget).toggle("blind", "easeInOutSine");
13            }
14        });
15
16        $(".list-collapsible > li > a").on("click", function (e) {
17            if ($(this).parent().find("ul").length === 0) {
18                return;
19            }
20
21            //Prevent click from following a link
22            e.preventDefault();
23            //Add or remove the class collapsed
24            $(this).toggleClass("is_collapsed");
25            // Collapse the li's
26            $(this).next().children().toggle("blind", "easeInOutSine");
27        });
28    }
29});