Ahh. You just haven't been around Python for long enough. Python used to get new server framework every other week. There was a Cambrian Explosion of them at one stage. Then it settled down. Javascript is still evolving. React has just kicked off a whole new iteration by putting the reactive/functional/immutable paradigm firmly on the agenda. That's going to take a couple of years to play out.

BTW, If you want to see what that combination looks like in a more suited language then look towards ClojureScript or Elm.