lib/web/mage/menu.js

this._on({
            /**
             * Prevent focus from sticking to links inside menu after clicking
             * them (focus should always stay on UL during navigation).
             */
            'mousedown .ui-menu-item > a': function (event) {
                event.preventDefault();
            },

            /**
             * Prevent focus from sticking to links inside menu after clicking
             * them (focus should always stay on UL during navigation).
             */
            '**click** .ui-state-disabled > a': function (event) {
                event.preventDefault();
            },

            /**
             * @param {jQuer.Event} event
             */
            'click .ui-menu-item:has(a)': function (event) {
                var target = $(event.target).closest('.ui-menu-item');

                if (!this.mouseHandled && target.not('.ui-state-disabled').length) {
                    this.select(event);

                    // Only set the mouseHandled flag if the event will bubble, see #9469.
                    if (!event.isPropagationStopped()) {
                        this.mouseHandled = true;
                    }

                    // Open submenu on click
                    if (target.has('.ui-menu').length) {
                        this.expand(event);
                    } else if (!this.element.is(':focus') &&
                        $(this.document[0].activeElement).closest('.ui-menu').length
                    ) {
                        // Redirect focus to the menu
                        this.element.trigger('focus', [true]);

                        // If the active item is on the top level, let it stay active.
                        // Otherwise, blur the active item since it is no longer visible.
                        if (this.active && this.active.parents('.ui-menu').length === 1) { //eslint-disable-line
                            clearTimeout(this.timer);
                        }
                    }
                }
            },
            'click .ui-menu-item': function (event) {
                var target = $(event.currentTarget),
                    submenu = this.options.menus,
                    ulElement,
                    ulElementWidth,
                    width,
                    targetPageX,
                    rightBound;

                if (target.has(submenu)) {
                    ulElement = target.find(submenu);
                    ulElementWidth = ulElement.outerWidth(true);
                    width = target.outerWidth() * 2;
                    targetPageX = target.offset().left;
                    rightBound = $(window).width();

                    if (ulElementWidth + width + targetPageX > rightBound) {
                        ulElement.addClass('submenu-reverse');
                    }

                    if (targetPageX - ulElementWidth < 0) {
                        ulElement.removeClass('submenu-reverse');
                    }
                }

                // Remove ui-state-active class from siblings of the newly focused menu item
                // to avoid a jump caused by adjacent elements both having a class with a border
                target.siblings().children('.ui-state-active').removeClass('ui-state-active');
                this.focus(event, target);
            },

            /**
             * @param {jQuery.Event} event
             */
            'mouseleave': function (event) {
                this.collapseAll(event, true);
            },

            /**
             * Mouse leave.
             */
            'mouseleave .ui-menu': 'collapseAll'
        });

        categoryParent = this.element.find('.all-category');
        html = $('html');

        categoryParent.remove();

        if (html.hasClass('nav-open')) {
            html.removeClass('nav-open');
            setTimeout(function () {
                html.removeClass('nav-before-open');
            }, 300);
        }
    }