I am using mod_rewrite to remap the URLs in my website in the following format:

http://www.mydomain.com/health/54856

http://www.mydomain.com/economy/strategy/911025/

http://www.mydomain.com/tags/obama/new

The problem is that I am making AJAX calls to a file: http://www.mydomain.com/login.php

And I don't want to write the FULL url or even use the ../ trick because there isn't a fixed level of folders.

So, what i want is something to access the login.php from the root, whatever the domain name is:

 $.ajax({
    type: "POST",
    url: "http://www.mydomain.com/login.php"
 });