I recently commented on a post from Joshua Eichorn looking at
caching javascript files. In the post he highlights the savings that can be made in terms of bandwidth.
What can you do though if you want to prevent javascript from caching? The php manual has some useful suggestions.
The header function is probably the best approach
<?phpheader("Cache-Control: no-cache, must-revalidate");
// HTTP/1.1header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
// Date in the past?>
This should force a browser to re-access a file each time it is needed. Remember though that headers must be set before any content is sent to the browser - that includes blank lines so be careful.