If you use a <script> tag then you will get the URL/page where the <script> tag is in as the referer.

example: if index.php has:

<script src="spy.php">

Then you'll always get index.php as the referer. This is because the user was on index.php when the HTTP request for spy.php was made.

If you want to get the site the user came from, then you have to save their referer in index.php. You can either append this data to your script src, or save it directly.

eg:

in index.php use:

Then in referer.php retrieve the site the user came from via:


Or you can just include spy.php in your PHP file:


This reduces the HTTP requests/bandwidth to your server.

One thing I noticed is the your spy.php gives non-js output. This will cause any JavaScript debuggers on the HTTP Client (users browsers) to display error messages.
What you want to do is give out a header('Content-Type: text/js'); and also reduce output to a format such as JSON or just JS. If viewed directly, you can still read the output and thus do your own debugging...