Send a GET/POST/AJAX request to a "File" Not Url On A Server

Send a GET/POST/AJAX request to a "File" Not Url On A Server

Is this possible in jQuery? From what I'm seeing you can only use a url in $.get(url, ..) or $.post(url, ..). Instead I want to do either or to a file on the server like $.get(filename.php, ...) or $.ajax(filename.php, ..). This php file is returning information. How can I do this?