addActionsFilters(); * * That's it. */ public function addActionsFilters() { // Modify calendar to support Bootstrap 4 style. add_filter('get_calendar', [$this, 'modifyCalendarWidget'], 10, 1); }// addActionsFilters /** * Modify calendar widget. * * @access private Do not access this method directly. This is for hook callback not for direct call. * @param string $calendar The WordPress original calendar widget. */ public function modifyCalendarWidget($calendar) { $new_calendar = preg_replace('#('; return $new_calendar; }// modifyCalendarWidget } }