flatkit-html5-admin/scripts/ui-nav.js

(function ($) {
  "use strict";
  
  $(document).on('click', '[ui-nav] a', function (e) {
    var $this = $(e.target), $active, $li;
    $this.is('a') || ($this = $this.closest('a'));
    
    $li = $this.parent();
    $active = $li.siblings( ".active" );
    $li.toggleClass('active');
    $active.removeClass('active');
  });
})(jQuery);