public function addOnReady($js)
    {
        if ($js instanceof jQuery_Chain) {
            $js = $js->getString();
        }
        if (!$this->atk4_initialised) {
            return parent::addOnReady($js);
        }

        $this->app->template->appendHTML('document_ready', "$.atk4(function(){ ".$js."; });\n");

        return $this;
    }