I’ve seen a few ways that you can make a javascript file include other javascript files, but they all seem pretty hacky – mostly they involve tacking the javascript file onto the end of the current document and then loading it in some way.
Why doesn’t javascript just include a simple “load this file and execute the script in it” include directive? It’s not like this is a new concept. I know that everyone is excited about doing everything in HTML5 with javascript etc, but isn’t it going to be hard if you have to hack around omission of basic functionality like this?
I can’t see how it would be a security concern, since a web page can include as many javascript files as it likes, and they all get executed anyway.
The main problems with the current inclusion system (ie, add additional script tags) involve latency. Since a script tag can insert code at the point of inclusion, as soon as a script tag is encountered, further parsing has to more-or-less stop until the JS downloads and is executed (although the browser can continue to fetch resources in parallel). If the JS decides to run an inclusion, you’ve just added more latency on top of this – now you can’t even fetch your scripts in parallel.
Basically, it’s trying to solve a problem that doesn’t exist (since JS can already tack on additional script tags to do an inclusion), while making the latency problem worse. There are javascript minifiers out there that can merge JS files; you should look into using those instead, as they will help improve latency issues as well.