updateFacets events - prestashop 1.7

  if(typeof prestashop !== 'undefined') {
                prestashop.on(
                  'updateFacets',
                  function (event) {

                    $("#js-product-list-bottom").append('<div id="page-preloader" style="display:block"></div>');
                   
                  
                  }
                );
            }