How to query a STUN server with JavaScript to get public IP and Port?

I am trying to find some code example to query a STUN server to get my public IP and Port, using JavaScript. Perhaps using the server at

http://www.stunserver.org

While the STUN specification is explained here http://www.ietf.org/rfc/rfc3489.txt ( this is a long document, obviously I don't expect you to read it), I have been unable to find any code example at all, which would make my life easier. Something like

function getMyIPAndPort() {
//query stun server for it
}

Thank you