External javascript libraries and scripts pose a potential security risk to your UnionCloud site if used in a malicious way. 

To counter this, we have built in the provision for you to disable any external JS scripts from use across your website. 

The checkbox is ocated in Admin > Setup > CMS > Disable external JS 

Please note: Once checked, if you have any existing external javascript anywhere across your site, this will not stop those from working, it will only disallow any new code that is added. 

On this basis, if you have this option checked but you need to add some external javascript, simply uncheck the box, add your code and then recheck.