## Summary
This PR bumps Flow all the way to the latest 0.245.2.
Most of the suppressions comes from Flow v0.239.0's change to include
undefined in the return of `Array.pop`.
I also enabled `react.custom_jsx_typing=true` and added custom jsx
typing to match the old behavior that `React.createElement` is
effectively any typed. This is necessary since various builtin
components like `React.Fragment` is actually symbol in the React repo
instead of `React.AbstractComponent<...>`. It can be made more accurate
by customizing the `React$CustomJSXFactory` type, but I will leave it to
the React team to decide.
## How did you test this change?
`yarn flow` for all the renderers
## Overview
Updates `eslint-plugin-jest` and enables the recommended rules with some
turned off that are unhelpful.
The main motivations is:
a) we have a few duplicated tests, which this found an I deleted
b) making sure we don't accidentally commit skipped tests
This disables symbol renaming in production builds. The original
variable and function names are preserved. All other forms of
compression applied by Closure (dead code elimination, inlining, etc)
are unchanged — the final program is identical to what we were producing
before, just in a more readable form.
The motivation is to make it easier to debug React issues that only
occur in production — the same reason we decided to start shipping
sourcemaps in #28827 and #28827.
However, because most apps run their own minification step on their npm
dependencies, it's not necessary for us to minify the symbols before
publishing — it'll be handled the app, if desired.
This is the same strategy Meta has used to ship React for years. The
React build itself has unminified symbols, but they get minified as part
of Meta's regular build pipeline.
Even if an app does not minify their npm dependencies, gzip covers most
of the cost of symbol renaming anyway.
This saves us from having to ship sourcemaps, which means even apps that
don't have sourcemaps configured will be able to debug the React build
as easily as they would any other npm dependency.
In React 19 React will finally stop publishing UMD builds. This is
motivated primarily by the lack of use of UMD format and the added
complexity of maintaining build infra for these releases. Additionally
with ESM becoming more prevalent in browsers and services like esm.sh
which can host React as an ESM module there are other options for doing
script tag based react loading.
This PR removes all the UMD build configs and forks.
There are some fixtures that still have references to UMD builds however
many of them already do not work (for instance they are using legacy
features like ReactDOM.render) and rather than block the removal on
these fixtures being brought up to date we'll just move forward and fix
or removes fixtures as necessary in the future.
Follow up to #28783 and #28786.
Since we've changed the implementations of these we can rename them to
something a bit more descriptive while we're at it, since anyone
depending on them will need to upgrade their code anyway.
"react" with no condition:
`__CLIENT_INTERNALS_DO_NOT_USE_OR_WARN_USERS_THEY_CANNOT_UPGRADE`
"react" with "react-server" condition:
`__SERVER_INTERNALS_DO_NOT_USE_OR_WARN_USERS_THEY_CANNOT_UPGRADE`
"react-dom":
`__DOM_INTERNALS_DO_NOT_USE_OR_WARN_USERS_THEY_CANNOT_UPGRADE`
## Summary
`isInputPending` is not in use. This PR cleans up the flags controlling
its gating and parameters to simplify Scheduler.
Makes `frameYieldMs` feature flag static, set to 10ms in www, which we
found built on the wins provided by a broader yield interval via
`isInputPending`. Flag remains set to 5ms in OSS builds.
## How did you test this change?
`yarn test Scheduler`
## Summary
these were removed in https://github.com/facebook/react/pull/26617. adds
them back so we can conduct another experiment.
## How did you test this change?
`yarn test-www`
It seems worthwhile to me to run a test to experiment with different
expiration times. This moves the expiration times for scheduler and
reconciler into FeatureFlags for the facebook build. Non-facebook should
not be affected by these changes.
## Summary
Follow up from #27717 based on feedback to rename the fork module itself
## How did you test this change?
- `yarn build`
- `yarn test
packages/scheduler/src/__tests__/SchedulerUMDBundle-test.internal.js`
Co-authored-by: Jack Pope <jackpope@meta.com>
## Summary
It's not clear to me why we currently create a new TaskController in
`runTask` – ultimately, we use the same signal and priority from the
original created in `unstable_scheduleCallback`
## How did you test this change?
```
yarn test SchedulerPostTask
```
## Summary
passing both a signal and a priority to `postTask`/`yield` in chrome
causes memory to spike and potentially causes OOMs. a fix for this has
landed in chrome 118, but we can avoid the issue in earlier versions by
setting priority on just the TaskController instead.
https://bugs.chromium.org/p/chromium/issues/detail?id=1469367
## How did you test this change?
```
yarn test SchedulerPostTask
```
## Summary
`scheduler.yield` is entering [Origin Trial soon in Chrome
115](https://chromestatus.com/feature/6266249336586240). This diff adds
it to `SchedulerPostTask` when scheduling continuations to allow Origin
Trial participation for early feedback on the new API.
It seems the difference here versus the current use of `postTask` will
be minor – the intent behind `scheduler.yield` seems to mostly be better
ergonomics for scheduling continuations, but it may be interesting to
see if the follow aspect of it results in any tangible difference in
scheduling (from
[here](https://github.com/WICG/scheduling-apis/blob/main/explainers/yield-and-continuation.md#introduction)):
> To mitigate yielding performance penalty concerns, UAs prioritize
scheduler.yield() continuations over tasks of the same priority or
similar task sources.
## How did you test this change?
```
yarn test SchedulerPostTask
```
To wait for the microtask queue to empty, our internal test helpers
schedule an arbitrary task using `setImmediate`. It doesn't matter what
kind of task it is, only that it's a separate task from the current one,
because by the time it fires, the microtasks for the current event will
have already been processed.
The issue with `setImmediate` is that Jest mocks it. Which can lead to
weird behavior.
I've changed it to instead use a message event, via the MessageChannel
implementation exposed by the `node:worker_threads` module.
We should consider doing this in the public implementation of `act`,
too.
(This only affects our own internal repo; it's not a public API.)
I think most of us agree this is a less confusing name. It's possible
someone will confuse it with `console.log`. If that becomes a problem we
can warn in dev or something.
This converts some of our test suite to use the `waitFor` test pattern,
instead of the `expect(Scheduler).toFlushAndYield` pattern. Most of
these changes are automated with jscodeshift, with some slight manual
cleanup in certain cases.
See #26285 for full context.
This converts some of our test suite to use the `waitFor` test pattern,
instead of the `expect(Scheduler).toFlushAndYield` pattern. Most of
these changes are automated with jscodeshift, with some slight manual
cleanup in certain cases.
See #26285 for full context.
## Summary
- yarn.lock diff +-6249, **small pr**
- use jest-environment-jsdom by default
- uncaught error from jsdom is an error object instead of strings
- abortSignal.reason is read-only in jsdom and node,
https://developer.mozilla.org/en-US/docs/Web/API/AbortSignal/reason
## How did you test this change?
ci green
---------
Co-authored-by: Sebastian Silbermann <silbermann.sebastian@gmail.com>
The old version of prettier we were using didn't support the Flow syntax
to access properties in a type using `SomeType['prop']`. This updates
`prettier` and `rollup-plugin-prettier` to the latest versions.
I added the prettier config `arrowParens: "avoid"` to reduce the diff
size as the default has changed in Prettier 2.0. The largest amount of
changes comes from function expressions now having a space. This doesn't
have an option to preserve the old behavior, so we have to update this.
This enables the "exact_empty_objects" setting for Flow which makes
empty objects exact instead of building up the type as properties are
added in code below. This is in preparation to Flow 191 which makes this
the default and removes the config.
More about the change in the Flow blog
[here](https://medium.com/flow-type/improved-handling-of-the-empty-object-in-flow-ead91887e40c).
This setting is an incremental path to the next Flow version enforcing
type annotations on most functions (except some inline callbacks).
Used
```
node_modules/.bin/flow codemod annotate-functions-and-classes --write .
```
to add a majority of the types with some hand cleanup when for large
inferred objects that should just be `Fiber` or weird constructs
including `any`.
Suppressed the remaining issues.
Builds on #25918
Hermes parser is the preferred parser for Flow code going forward. We
need to upgrade to this parser to support new Flow syntax like function
`this` context type annotations or `ObjectType['prop']` syntax.
Unfortunately, there's quite a few upgrades here to make it work somehow
(dependencies between the changes)
- ~Upgrade `eslint` to `8.*`~ reverted this as the React eslint plugin
tests depend on the older version and there's a [yarn
bug](https://github.com/yarnpkg/yarn/issues/6285) that prevents
`devDependencies` and `peerDependencies` to different versions.
- Remove `eslint-config-fbjs` preset dependency and inline the rules,
imho this makes it a lot clearer what the rules are.
- Remove the turned off `jsx-a11y/*` rules and it's dependency instead
of inlining those from the `fbjs` config.
- Update parser and dependency from `babel-eslint` to `hermes-eslint`.
- `ft-flow/no-unused-expressions` rule replaces `no-unused-expressions`
which now allows standalone type asserts, e.g. `(foo: number);`
- Bunch of globals added to the eslint config
- Disabled `no-redeclare`, seems like the eslint upgrade started making
this more precise and warn against re-defined globals like
`__EXPERIMENTAL__` (in rollup scripts) or `fetch` (when importing fetch
from node-fetch).
- Minor lint fixes like duplicate keys in objects.
* Facebook -> Meta in copyright
rg --files | xargs sed -i 's#Copyright (c) Facebook, Inc. and its affiliates.#Copyright (c) Meta Platforms, Inc. and affiliates.#g'
* Manual tweaks
- method unbinding is no longer supported in Flow for soundness, this added a bunch of suppressions
- Flow now prevents objects to be supertypes of interfaces/classes
ghstack-source-id: d7749cbad8
Pull Request resolved: https://github.com/facebook/react/pull/25412
This upgrade made more expressions invalidate refinements. In some
places this lead to a large number of suppressions that I automatically
suppressed and should be followed up on when the code is touched.
I think most of them might require either manual annotations or moving
a value into a const to allow refinement.
ghstack-source-id: a45b40abf0
Pull Request resolved: https://github.com/facebook/react/pull/25410
Enables well formed exports for /scheduler. Some of the modules there were missing `@flow` and were therefore completely unchecked (despite some spurious types sprinkled around).
* Internal `act`: Unwrapping resolved promises
This update our internal implementation of `act` to support React's new
behavior for unwrapping promises. Like we did with Scheduler, when
something suspends, it will yield to the main thread so the microtasks
can run, then continue in a new task.
I need to implement the same behavior in the public version of `act`,
but there are some additional considerations so I'll do that in a
separate commit.
* Move throwException to after work loop resumes
throwException is the function that finds the nearest boundary and
schedules it for a second render pass. We should only call it right
before we unwind the stack — not if we receive an immediate ping and
render the fiber again.
This was an oversight in 8ef3a7c that I didn't notice because it happens
to mostly work, anyway. What made me notice the mistake is that
throwException also marks the entire render phase as suspended
(RootDidSuspend or RootDidSuspendWithDelay), which is only supposed to
be happen if we show a fallback. One consequence was that, in the
RootDidSuspendWithDelay case, the entire commit phase was blocked,
because that's the exit status we use to block a bad fallback
from appearing.
* Use expando to check whether promise has resolved
Add a `status` expando to a thrown thenable to track when its value has
resolved.
In a later step, we'll also use `value` and `reason` expandos to track
the resolved value.
This is not part of the official JavaScript spec — think of
it as an extension of the Promise API, or a custom interface that is a
superset of Thenable. However, it's inspired by the terminology used
by `Promise.allSettled`.
The intent is that this will be a public API — Suspense implementations
can set these expandos to allow React to unwrap the value synchronously
without waiting a microtask.
* Scaffolding for `experimental_use` hook
Sets up a new experimental hook behind a feature flag, but does not
implement it yet.
* use(promise)
Adds experimental support to Fiber for unwrapping the value of a promise
inside a component. It is not yet implemented for Server Components,
but that is planned.
If promise has already resolved, the value can be unwrapped
"immediately" without showing a fallback. The trick we use to implement
this is to yield to the main thread (literally suspending the work
loop), wait for the microtask queue to drain, then check if the promise
resolved in the meantime. If so, we can resume the last attempted fiber
without unwinding the stack. This functionality was implemented in
previous commits.
Another feature is that the promises do not need to be cached between
attempts. Because we assume idempotent execution of components, React
will track the promises that were used during the previous attempt and
reuse the result. You shouldn't rely on this property, but during
initial render it mostly just works. Updates are trickier, though,
because if you used an uncached promise, we have no way of knowing
whether the underlying data has changed, so we have to unwrap the
promise every time. It will still work, but it's inefficient and can
lead to unnecessary fallbacks if it happens during a discrete update.
When we implement this for Server Components, this will be less of an
issue because there are no updates in that environment. However, it's
still better for performance to cache data requests, so the same
principles largely apply.
The intention is that this will eventually be the only supported way to
suspend on arbitrary promises. Throwing a promise directly will
be deprecated.
* Yield to main thread if continuation is returned
Instead of using an imperative method `requestYield` to ask Scheduler to
yield to the main thread, we can assume that any time a Scheduler task
returns a continuation callback, it's because it wants to yield to the
main thread. We can assume the task already checked some condition that
caused it to return a continuation, so we don't need to do any
additional checks — we can immediately yield and schedule a new task
for the continuation.
The replaces the `requestYield` API that I added in ca990e9.
* Move unwind after error into main work loop
I need to be able to yield to the main thread in between when an error
is thrown and when the stack is unwound. (This is the motivation behind
the refactor, but it isn't implemented in this commit.) Currently the
unwind is inlined directly into `handleError`.
Instead, I've moved the unwind logic into the main work loop. At the
very beginning of the function, we check to see if the work-in-progress
is in a "suspended" state — that is, whether it needs to be unwound. If
it is, we will enter the unwind phase instead of the begin phase.
We only need to perform this check when we first enter the work loop:
at the beginning of a Scheduler chunk, or after something throws. We
don't need to perform it after every unit of work.
* Yield to main thread whenever a fiber suspends
When a fiber suspends, we should yield to the main thread in case the
data is already cached, to unblock a potential ping event.
By itself, this commit isn't useful because we don't do anything special
in the case where to do receive an immediate ping event. I've split this
out only to demonstrate that it doesn't break any existing behavior.
See the next commit for full context and motivation.
* Resume immediately pinged fiber without unwinding
If a fiber suspends, and is pinged immediately in a microtask (or a
regular task that fires before React resumes rendering), try rendering
the same fiber again without unwinding the stack. This can be super
helpful when working with promises and async-await, because even if the
outermost promise hasn't been cached before, the underlying data may
have been preloaded. In many cases, we can continue rendering
immediately without having to show a fallback.
This optimization should work during any concurrent (time-sliced)
render. It doesn't work during discrete updates because those are
semantically required to finish synchronously — those get the current
behavior.
We need a way to yield control of the main thread and schedule a
continuation in a separate macrotask. (This is related to some Suspense
optimizations we have planned.)
Our solution needs account for how Scheduler is implemented. Scheduler
tasks are not 1:1 with real browser macrotasks — many Scheduler "tasks"
can be executed within a single browser task. If a Scheduler task yields
control and posts a continuation, but there's still time left in the
frame, Scheduler will execute the continuation immediately
(synchronously) without yielding control back to the main thread. That's
not what we want — we want to schedule a new macrotask regardless of
where we are in the browser's render cycle.
There are several ways we could approach this. What I ended up doing was
adding a new Scheduler method `unstable_requestYield`. (It's similar to
the existing `unstable_requestPaint` that we use to yield at the end of
the frame.)
It works by setting the internal start time of the current work loop to
a large negative number, so that when the `shouldYield` call computes
how much time has elapsed, it's guaranteed to exceed the deadline. The
advantage of doing it this way is that there are no additional checks in
the normal hot path of the work loop.
The existing layering between Scheduler and React DOM is not ideal. None
of the APIs are public, so despite the fact that Scheduler is a separate
package, I consider that a private implementation detail, and think of
them as part of the same unit.
So for now, though, I think it makes sense to implement this macrotask
logic directly inside of Scheduler instead of layering it on top.
The rough eventual plan for Scheduler is turn it into a `postTask`
prollyfill. Because `postTask` does not yet have an equivalent for
`shouldYield`, we would split that out into its own layer, perhaps
directly inside the reconciler. In that world, the macrotask logic I've
added in this commit would likely live in that same layer. When the
native `postTask` is available, we may not even need any additional
logic because it uses actual browser tasks.
Sam Zhou
Jan Kassens
Ricky
Andrew Clark
Josh Story
Sebastian Markbåge
sweetliquid
dan
Noah Lemen
Jack PopeandJack Pope
tjallingt
Samuel SuslaandDan Abramov
Ming Ye
c0dedance
bubucuo
Jan Kassens