WIP: Using React.createContext instead of ChildContext

[chrislloyd]

This is in respose to #5716. I'm tackling some of the smaller instances first just to get a sense of the project, coding style, tests etc.

It seemed like there was a little discussion about whether this change would alienate Preact and Inferno users however that's a decision for somebody else to make - I for one would prefer to take advantage of the latest and greatest React features.

The test plan is pretty simple - it's a refactoring so existing tests shouldn't break. Also completion milestone is removing prop-types as a dependency.

TODO

• headManager
• loadable
• router
• _documentProps

Note: I'm going to ignore the usage of legacy contextTypes in the examples as they don't add directly to Next's bundle size and I'm sure that each example library will have different best practices on how to update to React 17.

[timneutkens]

This is a breaking change, as users implement render() in a custom document: https://github.com/zeit/next.js#custom-document

[timneutkens]

The best way to do this is adding the provider to renderDocument in packages/next-server/server/render.tsx

[timneutkens]

I think the best way to go about moving this is gradually changing every component over, that makes sure the scope of the PR is smaller (targeted at a single feature) and makes it easier to see where the tests fail 👍

[chrislloyd]

Great yeah - seeing as headManager and documentProps are quite simple will keep this together (unless you feel strongly) but happy to create separate PRs for both loadable and router (which I suspect will be more involved). Thanks for the review!

[chrislloyd]

Also, is there a way to run the integration tests easily locally? They've been grinding my laptop to a halt because they spawn a tonne of Chrome processes.

[timneutkens]

seeing as headManager and documentProps are quite simple will keep this together (unless you feel strongly)

I'd like to split them for the reason that we can then compare bundle size / if everything is bundled correctly

[timneutkens]

Also, is there a way to run the integration tests easily locally? They've been grinding my laptop to a halt because they spawn a tonne of Chrome processes.

You can run individual tests:
https://github.com/zeit/next.js/blob/canary/contributing.md#to-run-tests

[chrislloyd]

Closing in favor of #5945. Again, thanks for the review @timneutkens!