External scripts working without being in directory

I have a gallery script that opens in a modal and sure enough it wants bootstrap and jquery that are included through cdn, but there’s also the actual package that glues it all together, which isn’t there. I was wondering if I should put my scrips in public and expect them to load up or something, matters not it really just work doesn’t it?

https://blueimp.github.io/Bootstrap-Image-Gallery/