// Bootstrap 3 CSS
loadjs(['https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.4.1/css/bootstrap.min.css'], { target: iframeWin });

// jQuery + Bootstrap 3 Javascript
loadjs(['https://code.jquery.com/jquery-3.4.1.min.js', 'https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.4.1/js/bootstrap.min.js'], 'core-preview', { async: false, target: iframeWin });