You mean javascript. Ain't no Java in here.
BTW I also worked on something that will keep trying to join a full server for you every 5 seconds automatically. It is not finished by any means, and needs a lot of polish, but the basic functionality works, and a simple refresh of the page will fix any bugs that popup.
http://userscripts.org/scripts/show/114219
Use at your own risk, but there shouldn't be any real risk.
To use it, install it, then you select a server in the server browser, click the big join button on the right, if its full you will get the error, but then the auto join button will show up. Click that and it will continue to try to join or stop when you click stop. If you get in a game it wont keep trying. It is for those times when there aren't any servers with good pings that you can get into easily, and this allows you to set it and forget it until you get in. At least until they setup queues or something again.