Very cool. Reminds me a bit of RoboCode that was created a while back from IBM DeveloperWorks (http://robocode.sourceforge.net/). This should be a fun way to practive JS.
In my first year CPSC classes I had an awesome prof who made learning fun. Rather than program boring text based games like tic-tac-toe we instead learned Java with projects such as RoboCode && Env3d (http://env3d.org/beta/showcase).
Great to see RoboCode for JS now too!