Last night I started going through learnyounode on recommendation of a colleague. Learnyounode is best described as a 1980s throwback text-based adventure game in which you slay the mighty JS dragons by completing a series increasingly difficult challenges. I say increasingly difficult, because so far, none of the challenges have taken more than 10 or 15 minutes.
Since I've most recently been in Scala code, the notion of passing functions around and async callbacks in general was not terribly difficult to grasp, and performing functional operations over arrays was second nature. I still have 4 more challenges to complete. Next I'm going to try Stream Adventure.