[v2] new API and new implementation with useMutableSource

[dai-shi]

• new API: useContext(context, selector)
• new implementation with useMutableSource in the RFC
• in TypeScript

Check list:

• implementation
• readme

[dai-shi]

Just did a quick benchmark. This is very simplified usage, and it may not reflect real use cases. react-redux-use-context-selector-2-keyed represents ff52b56 with useMutableSource-enabled (wip) React. (while others use React 16.8.6, so they are totally incomparable.)

[dai-shi]

Here's another trial. both v1 and v2 use facebook/react@b028a0b.

[dai-shi]

If we still need to use calculateChangedBits, we should stick with v1 without useMutableSource. That's very unfortunate though.

[dai-shi]

https://www.npmjs.com/package/use-context-selector/v/2.0.0-alpha.6

[dai-shi]

https://www.npmjs.com/package/use-context-selector/v/2.0.0-alpha.9

[dai-shi]

uMS will not land, and v1.3 already works well with concurrent rendering at its best. Closing.

[HansBrende]

@dai-shi the replacement for useMutableSource is useSyncExternalStore.... why not use that function instead?

[dai-shi]

It doesn't work as we want. It's "Sync" and its behavior isn't well in concurrent rendering.