It can sometimes be easy to inadvertently leak variables / functions into the global scope in your client side javascript - this one-liner will report all non-browser global keys and their values on the page - just paste into your chrome console.
For most sites you want to get the benefits of a CDN, but it is still a single point of failure. I came across this pattern recently though that allows you to fail over to a local file if the CDN library doesn’t load. Would probably have to take a different approach with CSS libraries though.
<!-- try to download from CDN --><script src="http://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script><!-- if failed, switch to local copy --><script>window.jQuery||document.write('<script src="local_server_path/jquery.min.js"></script>')</script>
Something I hope to explore more very soon is webpack, which might make this trick obsolete.
Update: It took me a while to find where I had originally found this idea, but I came across it again. Credit: http://minime.stephan-brumme.com/. They also have examples for several other popular client-side js libraries.
At my previous job we had several projects where we worked with MSSQL express, maybe with multiple databases. Here is a quick script to just backup all user (non-system) databases on the system, quickly and easily. It could probably be improved a bit, maybe better naming for the backups, but as a quick backup-all-the-things it works great.