Random number after js file include

Question

Hello, I have a problem with a page that includes two js files. In firebug it shows that every time the page loads those two files get included with the prefix ?_=someRandomNumber

I don't know where that random number is generated from and I guess it is the reason the files are not being cached and are downloaded each time the page is hit.

Here is the firebug snapshot

GET http://127.0.0.1:8500/file1.js?_=1251379620583
GET http://127.0.0.1:8500/file2.js?_=1251379620583

200 OK
 697ms jquery-1....2.min.js (line 19)
GET http://127.0.0.1:8500/file1.js?_=1251379622773
GET http://127.0.0.1:8500/file2.js?_=1251379622773

200 OK
 148ms

My include is very simple

<script type="text/javascript" src="file1.js"></script>
 <script type="text/javascript" src="file2.js"></script>

I am also using jQuery in the application.

Thanks!

Answer 1

It looks like current timestamp (or file's timestamp) and is most likely there to make sure the file is not cached.

Answer 2

This won't be a javascript issue, the source of this behaviour will be in whatever server-side technology you're using to generate the page.

Answer 3

Yes, the random number there is precisely to prevent your browser from caching the files. This is the general technique used when the developers have a resource which they keep updating and want the updates to be reflected.

Answer 4

Firebug is a developer tool, aiding development. It makes sure that any changes you make to a file aren't cached so that a new copy is requested everytime. If it didn't request a new version, and kept requesting an old version. Old buggy versions of code could be laoded as opposed to a new, bugless version.