Super awesome can't wait to show this to my boy - he is super ready to move on from the programming at khanacadamy so am trying to learn him some game libraries. However he doesn't feel that comfortable outside of the nice KhanAcademy web environment, so using a lot of jsfiddle sessions is a great way to teach. Thanks!
PS jds375 comment about being sure to activate unsafe scripts (click at top right of address bar) is worth noting