how to gzip one or more page

like:http://extjs.com/deploy/dev/examples/feed-viewer/view.html

it uses ext , as we know ext-all.js is so big nearly 500k . but when I watch in firebug it is only 125k , I know it is gziped server side , but when I watch the soruce code , there is nothing special , just

<script src="ext-all.js"></script>
as I know , if we want to gzip some file , it should be
<script src="ext-all.php"></script>

and in ext-all.php , we deal with ext-all.js.

so I confused how to do it.

I wonder if I expresses clearly , because my English is not so good.

Compressing data is something the server does, and then lets the client know that what it is about to receive is compressed.

They could have set up *.js to be parsed by PHP, or they have an automatic compressing filter (say a plugin for Apache) set up in the server that does it to everything.

It's not just limited to PHP.

thanks aedrin , I got the answer!

use .htaccess is a nice way.