how to add jquery and jquery ui in vanilla javascript code example

Example 1: how to import jquery in js file

var script = document.createElement('script');
script.src = 'https://code.jquery.com/jquery-3.4.1.min.js';
script.type = 'text/javascript';
document.getElementsByTagName('head')[0].appendChild(script);

Example 2: import jquery into js file

var script = document.createElement('script');
script.src = 'https://code.jquery.com/jquery-3.4.1.min.js';
script.type = 'text/javascript';
document.getElementsByTagName('head')[0].appendChild(script);