It is, but it's not written in javascript[1]. Flux came out when I was in the middle of developing it, and I spent hours reading about it, looking at it and playing with it, and it just didn't solve any problems that I had.

Note that the community's ideas of best-practices, and all of the ecosystem around react is changing at an absurd pace, but core react is fairly stable.

1: https://github.com/jasom/cl-fccs