Multiple external JavaScript files using one script tag

Question

I have seen on some websites they have one script tag but call multiple JS file e.g.

Answer 1

That loads a single JS file. The URLs just has multiple things that look like filenames in it.

There is a strong probability that the single JS file is built from multiple files by a server side script. If so, that is just a simple matter of…

1. parsing the filenames from the URL (split on commas)
2. sanity checking them
3. concatenating the files into the response

(and giving it a suitable Content-Type header).

It is inefficient to do that for every hit though, so make sure you implement sane caching. Both with HTTP response headers and on your server.