Is it by any means possible to read the browser session id using javascript?
you can receive the session id by issuing the following regular expression on document.cookie:
alert(document.cookie.match(/PHPSESSID=[^;]+/));
in my example the cookie name to store session id is PHPSESSID (php server), just replace the PHPSESSID with the cookie name that holds the session id. (configurable by the web server)