Mozilla Web Developer FAQ
you can see the http headers sent by the server by using the livehttpheaders extension or by using the web sniffer.

Headers() - Web APIs
in the following snippet we create a new headers object, adding some headers by passing the constructor an init object as an argument: var httpheaders = { 'content-type' : 'image/jpeg', 'accept-charset' : 'utf-8', 'x-my-custom-header' : 'zeke are cool' }; var myheaders = new headers(httpheaders); you can now create another headers object, passing it the first headers object as its init object: var secondheadersobj = new headers(myheaders); secondheadersobj.get('content-type'); // would return 'image/jpeg' — it inherits it from the first hea...

Index - Web APIs
to find out which mime type your server sends, look at page info, use extensions like livehttpheaders or a download manager like wget.

XSL Transformations in Mozilla FAQ - Web APIs
to find out which mime type your server sends, look at page info, use extensions like livehttpheaders or a download manager like wget.