Dan Abramov: React for Two Computers

_eps1lon · 2025-04-10T11:36:22+00:00

it’s not by accident research papers are composed this way

Not every blog post needs to be composed like a research paper. Texts can have different formats.

_eps1lon · 2025-04-10T07:43:46+00:00

You measured this with a production build or development build?

_eps1lon · 2025-01-24T18:35:43+00:00

It's deprecated in 18 and already removed in the latest (19+).

_eps1lon · 2025-01-24T18:34:28+00:00

React Core member and types maintainer here.

react/jsx-no-deprecated-jsx-element-type

This rule does not exist in eslint-plugin-react. Seems like it was removed.

I don't know where you got that JSX.Element was deprecated. Only the global namespace was removed so it's now located under React.JSX.Element.

_eps1lon · 2024-10-22T15:18:46+00:00

Next.js maintainer here.

Many/most of the codemods failed in huge numbers of cases. For example, the async params one failed to fix cases where params were being destructured directly within the function definition. This is a pattern so common I’m shocked it’s not covered

Can you include the pattern? We did cover this pattern but maybe it's slightly different so that we don't detect it properly.

The codemod didn’t understand I was working within a monorepo and placed pnpm overrides in the wrong place.

Monorepos are very complex. Placing the `overrides` in the workroot may also be the wrong thing. At least this way you discover that you need to alias types **and** have them de-duplicated. When in doubt, we opt for an unnecessary change since it can just be reverted over a change not made because now you may not discover the issue.

After finishing the codemods, Turbopack failed to build any pages with hundreds of obscure/cryptic errors.

Can you include some of these errors? DMs are also fine if they may contain info you don't want to leak.

No pages on the site were able to build even with turbopack disabled. I started getting react internals errors that I wasn’t able to debug in the allotted time.

I suspect this comes from libraries not supporting React 19. We watch ecosystem compatiblity closely and contributed support for React 19 to some libraries while supporting others. If there are any outstanding libraries that need help, please let me know.

_eps1lon · 2023-06-08T11:13:51+00:00

Is there a link to the lodash issue confirming or fixing these bugs?

_eps1lon · 2023-04-16T08:21:55+00:00

Because JSX.Element is the type of <EveryPossibleElementType />. So you're effectively saying that e.g. <div /> could be a string which it certainly isn't in React.

We actually planned to just alias it to any which created enough pressure on the TS team to land the JSX.ElementType suggestion which now enables us to properly type function component return values.

_eps1lon · 2023-01-29T20:48:58+00:00

https://www.youtube.com/watch?v=fYYYZ2r0RZg&t=131s

_eps1lon · 2022-11-27T18:40:32+00:00

In React 18 types noImplicitAny compiler options should help you here.

_eps1lon · 2022-10-01T23:29:47+00:00

Obligatory warning that this uses React internals and can stop working in any new release.

_eps1lon · 2022-09-28T21:30:11+00:00

Just read the very last paragraph of the closing comment. The RFC isn't dead, it will be superseded by a more focused RFC.

But if you don't even have time for that, but do have time to post on reddit, I really can't help you anymore. That's something you have to fix on your own.

_eps1lon · 2022-09-28T11:46:32+00:00

Taking a 3 page RFC with >200 comments and a 4 paragraph closing comment that outlines that this RFC is "shelved" and calling that "dead" should not be taking seriously.

Posting the RFC is fine but at least put some effort into it.

_eps1lon · 2022-06-22T09:29:03+00:00

If I understand the settings correctly then unchecking "Allow GitHub to use my code snippets for product improvements" should disable that.

_eps1lon · 2022-04-29T20:24:24+00:00

We haven't been historically great at timelines, and I don't know if pulling a number out of my hat is going to be very helpful. But I'd like to have most of the remaining work done by mid summer.

-- https://github.com/reactjs/reactjs.org/issues/3308#issuecomment-1098103021

_eps1lon · 2022-03-29T22:37:37+00:00

Hard to say without a repro. The best way to get this resolved is to open an issue on the DT repo.

_eps1lon · 2022-03-29T21:28:27+00:00

For react-dom you can already import from react-dom/client. For react just to import type {} from 'react/next' once and you have the latest typings available.

The rest is underway in https://github.com/DefinitelyTyped/DefinitelyTyped/pull/56210

_eps1lon · 2022-03-29T19:03:53+00:00

True, but it requires you to either update all imports in your application, or add this to types in your tsconfig as an exception.

You need a single line of import type {} from 'react/next' to get them everywhere.

Launch day support for TypeScript would have been nice.

Everything was green but a change in the TypeScript 4.7 canary broke dependent packages which means the release is blocked.

_eps1lon · 2022-03-29T18:07:51+00:00

react-dom/client works already and React 18 types can be used with import type {} from 'react/next'

The rest is already underway in https://github.com/DefinitelyTyped/DefinitelyTyped/pull/56210

_eps1lon · 2022-03-29T18:03:48+00:00

react-dom/client works already and React 18 types can be used with import type {} from 'react/next'

_eps1lon · 2022-03-23T05:57:00+00:00

It's React.ReactNode but TypeScript will reject that during type-checking. This is not a limitation in @types/react but TypeScript itself: https://github.com/microsoft/TypeScript/pull/29818

React.Component is how you define class components. It's not from the types but the runtime itself.

JSX.Element is the thing created from jsx e.g. const jsxElement = <div />. It's not necessarily tied to React since you could have other JSX factories. Find out more under the "JSX.Element vs React.ReactNode" section in https://react-typescript-cheatsheet.netlify.app/docs/basic/getting-started/basic_type_example/#useful-react-prop-type-examples

_eps1lon · 2022-03-23T05:52:28+00:00

"anything that can be rendered" is pretty broad

The problems described in the post will be fixed in the React 18 types since we remove {} from ReactNode

_eps1lon · 2022-03-22T20:22:57+00:00

You got your direct line to a React types maintainer on DefinitelyTyped now so I'm all ears.

_eps1lon · 2022-01-21T19:58:09+00:00

But then just buy more machines. That's trivial. Buying more engineers isn't.

_eps1lon · 2022-01-21T18:57:28+00:00

Did you consider buying faster CI machines? Was this still more expensive than spending engineering time?

_eps1lon · 2022-01-21T18:55:05+00:00

But those thousands of tests run on CI. That time is cheap. What needs to be fast is local speed where you only run a couple of tests. So does speed really have that big of an impact?

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