code: function(e) {
              e.preventDefault();
              var element = $(e.target);
              if (element.hasClass(faAngleUpClass)) {
                  element.addClass(faAngleDownClass);
                  element.removeClass(faAngleUpClass);
              } else {
                  element.addClass(faAngleUpClass);
                  element.removeClass(faAngleDownClass);
              }
          }
docs: collapse menu