Read Session Id using Javascript

Question

Is it by any means possible to read the browser session id using javascript?

Answer 1

Here's a short and sweet JavaScript function to fetch the session ID:

function session_id() {
    return /SESS\w*ID=([^;]+)/i.test(document.cookie) ? RegExp.$1 : false;
}

Or if you prefer a variable, here's a simple one-liner:

var session_id = /SESS\w*ID=([^;]+)/i.test(document.cookie) ? RegExp.$1 : false;

Should match the session ID cookie for PHP, JSP, .NET, and I suppose various other server-side processors as well.