What language is Khan Academy CS using?

What language is Khan Academy CS using?

References

Reference NO 1

http://www.khanacademy.org/talks-and-interviews/our-vision/v/khan-academy-computer-science-launch

Reference NO 2

http://www.khanacademy.org/cs/welcome-to-computer-science/882454257

Reference NO 3

http://stackoverflow.com/questions/15190606/what-language-is-khan-academy-cs-using

Reference NO 4

http://venturebeat.com/2012/08/14/khan-academy-computer-science/

Reference NO 5

http://lifehacker.com/5935322/khan-academy-computer-science-teaches-you-to-code-through-exploration

Reference NO 6

http://www.ghacks.net/2012/08/16/khan-academy-now-with-computer-science-courses/

Reference NO 7

http://www.wired.com/wiredenterprise/2012/08/khan-academy/

Reference NO 8

http://developers.slashdot.org/story/12/08/14/2019229/khan-academy-launches-computer-science-curriculum