Yeah! We have full curriculum around it, as well (Intro to JavaScript, Game development, and Natural Simulations): https://www.khanacademy.org/computing/computer-programming

It uses a real-time JavaScript editing framework that we're in the process of open sourcing: https://github.com/Khan/live-editor

A technical talk on the editor (a bit dated at this point, but most of the points still hold) can be found here: http://ejohn.org/blog/talk-khan-academy-computer-science/