[codelike]

I've just finished reading https://code.facebook.com/posts/1716776591680069/react-16-a-... and it provided lots of good insights into how you managed to roll out the new release. Thanks for the interesting write-up!

That blog post mentions your featureFlag approach, the initial dogfooding and then the gradual rollout. I'd be very interested to hear on top of that:

1. How did you approach the rewrite on the coding side? What I mean is: Did you just say "Okay, let's start from scratch and use the lessons learned from v1?" Or did you use a specific approach along along the lines of: "Let's structure our code based on these principles and ...?"

2. When you started the rewrite, how did you know in advance and make sure that the rewrite would be faster and have a smaller code-size?

3. Was your focus during the rewrite on a cleaner code base (and the performance improvements followed automatically) or was your focus on speed right from the start?

4. Any other lessons learned during the rewrite? Patterns and approaches that helped/didn't help during the coding?