public function registerCoreScripts($url = null, $position = CClientScript::POS_END)
    {
        if ($url === null) {
            $fileName = YII_DEBUG ? 'bootstrap.js' : 'bootstrap.min.js';
            $url = $this->getBootstrapUrl() . '/js/' . $fileName;
        }
        /** @var CClientScript $cs */
        $cs = Yii::app()->getClientScript();
        $cs->registerCoreScript('jquery');
        $cs->registerScriptFile($url, $position);
    }