[pso]

The same real world react app went from 40MB to 20MB.

They don't ship minified javascript to final app, but bytecode, which they say is 1/3 smaller (both minified). They have moved the parse and compile stages to ahead of time, making the VM smaller, and giving the bytecode benefit. The bytecode benefit also means a quicker time to live/first reponse from 4s to 2s in their example.

Link to the talk, from FB employee announcement made at React Conference today, 15 minutes length. Linked 2 mins in, because the audio is poor to start.

https://youtu.be/zEjqDWqeDdg?t=130

[js2]

Ah, gotcha. It's moving the parse/compile AOT that I missed. Naively, I'm still surprised they didn't start with JSC/V8 but maybe those engines carry a lot more in them than is needed. Thank you for the link.

[aylmao]

This is actually huge and will probably only get better, especially considering now they own their whole JS stack: the framework (React/RN), the language (Flow [1]) and now the VM.

It sounds like Hermes is exclusively for running React Native on mobile. They could start building React directly into Hermes— the reconciling algorithm for example, or maybe even some real parallelism.

Very curious to see how all this keeps evolving.

[1]: https://github.com/facebook/flow