The format is something like this; the php function fails to run if put as a .js file:

<script language="JavaScript" type="text/javascript" src="http://www.domainname.com/app/track.php?a=tr&cid=<?php echo $_GET['cid']; ?>"></script>

And I want the script to run on index page only. Modifying the common/html_header will make the script to run site-wide.

Any suggestions?

Thanks in advanced.