We already did this for Server References on the Client so this brings
us parity with that. This gives us some more flexibility with changing
the runtime implementation without having to affect the loaders.
We can also do more in the runtime such as adding `.bind()` support to
Server References.
I also moved the CommonJS Proxy creation into the runtime helper from
the register so that it can be handled in one place.
This lets us remove the forks from Next.js since the loaders can be
simplified there to just use these helpers.
This PR doesn't change the protocol or shape of the objects. They're
still specific to each bundler but ideally we should probably move this
to shared helpers that can be used by multiple bundler implementations.
Adds a development warning to complement the error introduced by
https://github.com/facebook/react/pull/27019.
We can detect and warn about async client components by checking the
prototype of the function. This won't work for environments where async
functions are transpiled, but for native async functions, it allows us
to log an earlier warning during development, including in cases that
don't trigger the infinite loop guard added in
https://github.com/facebook/react/pull/27019. It does not supersede the
infinite loop guard, though, because that mechanism also prevents the
app from crashing.
I also added a warning for calling a hook inside an async function. This
one fires even during a transition. We could add a corresponding warning
to Flight, since hooks are not allowed in async Server Components,
either. (Though in both environments, this is better handled by a lint
rule.)
Modern runtimes support native async/await, as does the version of Node
we use for our tests. To match how most of our users run React, this
disables the transpilation of async/await in our test suite.
Suspending with an uncached promise is not yet supported. We only
support suspending on promises that are cached between render attempts.
(We do plan to partially support this in the future, at least in certain
constrained cases, like during a route transition.)
This includes the case where a component returns an uncached promise,
which is effectively what happens if a Client Component is authored
using async/await syntax.
This is an easy mistake to make in a Server Components app, because
async/await _is_ available in Server Components.
In the current behavior, this can sometimes cause the app to crash with
an infinite loop, because React will repeatedly keep trying to render
the component, which will result in a fresh promise, which will result
in a new render attempt, and so on. We have some strategies we can use
to prevent this — during a concurrent render, we can suspend the work
loop until the promise resolves. If it's not a concurrent render, we can
show a Suspense fallback and try again at concurrent priority.
There's one case where neither of these strategies work, though: during
a sync render when there's no parent Suspense boundary. (We refer to
this as the "shell" of the app because it exists outside of any loading
UI.)
Since we don't have any great options for this scenario, we should at
least error gracefully instead of crashing the app.
So this commit adds a detection mechanism for render loops caused by
async client components. The way it works is, if an app suspends
repeatedly in the shell during a synchronous render, without committing
anything in between, we will count the number of attempts and eventually
trigger an error once the count exceeds a threshold.
In the future, we will consider ways to make this case a warning instead
of a hard error.
See https://github.com/facebook/react/issues/26801 for more details.
This uses the same mechanism as [large
strings](https://github.com/facebook/react/pull/26932) to encode chunks
of length based binary data in the RSC payload behind a flag.
I introduce a new BinaryChunk type that's specific to each stream and
ways to convert into it. That's because we sometimes need all chunks to
be Uint8Array for the output, even if the source is another array buffer
view, and sometimes we need to clone it before transferring.
Each type of typed array is its own row tag. This lets us ensure that
the instance is directly in the right format in the cached entry instead
of creating a wrapper at each reference. Ideally this is also how
Map/Set should work but those are lazy which complicates that approach a
bit.
We assume both server and client use little-endian for now. If we want
to support other modes, we'd convert it to/from little-endian so that
the transfer protocol is always little-endian. That way the common
clients can be the fastest possible.
So far this only implements Server to Client. Still need to implement
Client to Server for parity.
NOTE: This is the first time we make RSC effectively a binary format.
This is not compatible with existing SSR techniques which serialize the
stream as unicode in the HTML. To be compatible, those implementations
would have to use base64 or something like that. Which is what we'll do
when we move this technique to be built-in to Fizz.
This PR contains a regression test and two separate fixes: a targeted
fix, and a more general one that's designed as a last-resort guard
against these types of bugs (both bugs in app code and bugs in React).
I confirmed that each of these fixes separately are sufficient to fix
the regression test I added.
We can't realistically detect all infinite update loop scenarios because
they could be async; even a single microtask can foil our attempts to
detect a cycle. But this improves our strategy for detecting the most
common kind.
See commit messages for more details.
Suppose that you have this setup for devtools test:
```
// @reactVersion <= 18.1
// @reactVersion >= 17.1
```
With previous implementation, the accumulated condition will be `"<=
18.1" && ">= 17.1"`, which is just `">= 17.1"`, when evaluated. That's
why we executed some tests for old versions of react on main (and
failed).
With these changes the resulting condition will be `"<= 18.1 >= 17.1"`,
not using `&&`, because semver does not support this operator. All
currently failing tests will be skipped now as expected.
Also increased timeout value for shell server to start
## Summary
Running `yarn test --project devtools --build` currently skips all
non-gated (without `@reactVersion` directives) devtools tests. This is
not expected behaviour, these changes are fixing it.
There were multiple related PRs to it:
- https://github.com/facebook/react/pull/26742
- https://github.com/facebook/react/pull/25712
- https://github.com/facebook/react/pull/24555
With these changes, the resulting behaviour will be:
- If `REACT_VERSION` env variable is specified:
- jest will not include all non-gated test cases in the test run
- jest will run only a specific test case, when specified
`REACT_VERSION` value satisfies the range defined by `@reactVersion`
directives for this test case
- If `REACT_VERSION` env variable is not specified, jest will run all
non-gated tests:
- jest will include all non-gated test cases in the test run
- jest will run all non-gated test cases, the only skipped test cases
will be those, which specified the range that does not include the next
stable version of react, which will be imported from `ReactVersions.js`
## How did you test this change?
Running `profilingCache` test suite without specifying `reactVersion`
now skips gated (>= 17 & < 18) test
<img width="1447" alt="Screenshot 2023-06-15 at 11 18 22"
src="https://github.com/facebook/react/assets/28902667/cad58994-2cb3-44b3-9eb2-1699c01a1eb3">
Running `profilingCache` test suite with specifying `reactVersion` to
`17` now runs this test case and skips others correctly
<img width="1447" alt="Screenshot 2023-06-15 at 11 20 11"
src="https://github.com/facebook/react/assets/28902667/d308960a-c172-4422-ba6f-9c0dbcd6f7d5">
Running `yarn test --project devtools ...` without specifying
`reactVersion` now runs all non-gated test cases
<img width="398" alt="Screenshot 2023-06-15 at 12 25 12"
src="https://github.com/facebook/react/assets/28902667/2b329634-0efd-4c4c-b460-889696bbc9e1">
Running `yarn test --project devtools ...` with specifying
`reactVersion` (to `17` in this example) now includes only gated tests
<img width="414" alt="Screenshot 2023-06-15 at 12 26 31"
src="https://github.com/facebook/react/assets/28902667/a702c27e-4c35-4b12-834c-e5bb06728997">
## Summary
- Updated `webpack` (and all related packages) to v5 in
`react-devtools-*` packages.
- I haven't touched any `TODO (Webpack 5)`. Tried to poke it, but each
my attempt failed and parsing hook names feature stopped working. I will
work on this in a separate PR.
- This work is one of prerequisites for updating Firefox extension to
manifests v3
related PRs:
https://github.com/facebook/react/pull/22267https://github.com/facebook/react/pull/26506
## How did you test this change?
Tested on all surfaces, explicitly checked that parsing hook names
feature still works.
This isn't really meant to be actually used, there are many issues with
this approach, but it shows the capabilities as a proof-of-concept.
It's a new reference implementation package `react-server-dom-esm` as
well as a fixture in `fixtures/flight-esm` (fork of `fixtures/flight`).
This works pretty much the same as pieces we already have in the Webpack
implementation but instead of loading modules using Webpack on the
client it uses native browser ESM.
To really show it off, I don't use any JSX in the fixture and so it also
doesn't use Babel or any compilation of the files.
This works because we don't actually bundle the server in the reference
implementation in the first place. We instead use [Node.js
Loaders](https://nodejs.org/api/esm.html#loaders) to intercept files
that contain `"use client"` and `"use server"` and replace them. There's
a simple check for those exact bytes, and no parsing, so this is very
fast.
Since the client isn't actually bundled, there's no module map needed.
We can just send the file path to the file we want to load in the RSC
payload for client references.
Since the existing reference implementation for Node.js already used ESM
to load modules on the server, that all works the same, including Server
Actions. No bundling.
There is one case that isn't implemented here. Importing a `"use
server"` file from a Client Component. We don't have that implemented in
the Webpack reference implementation neither - only in Next.js atm. In
Webpack it would be implemented as a Webpack loader.
There are a few ways this can be implemented without a bundler:
- We can intercept the request from the browser importing this file in
the HTTP server, and do a quick scan for `"use server"` in the file and
replace it just like we do with loaders in Node.js. This is effectively
how Vite works and likely how anyone using this technique would have to
support JSX anyway.
- We can use native browser "loaders" once that's eventually available
in the same way as in Node.js.
- We can generate import maps for each file and replace it with a
pointer to a placeholder file. This requires scanning these ahead of
time which defeats the purposes.
Another case that's not implemented is the inline `"use server"` closure
in a Server Component. That would require the existing loader to be a
bit smarter but would still only "compile" files that contains those
bytes in the fast path check. This would also happen in the loader that
already exists so wouldn't do anything substantially different than what
we currently have here.
## Overview
Does a few things:
- Renames `enableSyncDefaultUpdates` to
`forceConcurrentByDefaultForTesting`
- Changes the way it's used so it's dead-code eliminated separate from
`allowConcurrentByDefault`
- Deletes a bunch of the gated code
The gates that are deleted are unnecessary now. We were keeping them
when we originally thought we would come back to being concurrent by
default. But we've shifted and now sync-by default is the desired
behavior long term, so there's no need to keep all these forked tests
around.
I'll follow up to delete more of the forked behavior if possible.
Ideally we wouldn't need this flag even if we're still using
`allowConcurrentByDefault`.
With df12d7eac4 I accidentally made it so
that tests aren't run with the 2 variant modes for most
SchedulerFeatureFlags anymore. This fixes it with the same approach as
ee4233bdbc.
Test Plan:
Run and notice the boolean flags follow the variant:
```
yarn test-www --variant=true
yarn test-www --variant=false
```
The bindings upstream in Relay has been removed so we don't need these
builds anymore. The idea is to revisit an FB integration of Flight but
it wouldn't use the Relay specific bindings. It's a bit unclear how it
would look but likely more like the OSS version so not worth keeping
these around.
The `dom-relay` name also included the FB specific Fizz implementation
of the streaming config so I renamed that to `dom-fb`. There's no Fizz
implementation for Native yet so I just removed `native-relay`.
We created a configurable fork for how to encode the output of Flight
and the Relay implementation encoded it as JSON objects instead of
strings/streams. The new implementation would likely be more stream-like
and just encode it directly as string/binary chunks. So I removed those
indirections so that this can just be declared inline in
ReactFlightServer/Client.
## Summary
To support incremental adoption of bridgeless logic we want to default
to using these globals whenever they're available.
## How did you test this change?
https://github.com/facebook/react-native/pull/37410
The idea is that the default `yarn test` command should be the one that
includes the most bleeding edge features, because during development you
probably want as many features enabled as possible.
That used to be `www-modern` but nowadays it's `experimental` because
we've landed a bunch of async actions stuff in experimental but it isn't
yet being tested at Meta.
So this switches the default to `experimental`.
Just a small upgrade to keep us current and remove unused suppressions
(probably fixed by some upgrade since).
- `*` is no longer allowed and has been an alias for `any` for a while
now.
- The whole project root is included by default anyway, the include
section should be redundant and just misleading.
- The generated ignore paths ignore more than intended as they didn't
escape the `.` for regex.
Test Plan:
- wait for CI
- tested the ignore pattern change with renaming files and seeing the
expected files ignored for flow
This automatically exposes `$$FORM_ACTIONS` on Server References coming
from Flight. So that when they're used in a form action, we can encode
the ID for the server reference as a hidden field or as part of the name
of a button.
If the Server Action is a bound function it can have complex data
associated with it. In this case this additional data is encoded as
additional form fields.
To process a POST on the server there's now a `decodeAction` helper that
can take one of these progressive posts from FormData and give you a
function that is prebound with the correct closure and FormData so that
you can just invoke it.
I updated the fixture which now has a "Server State" that gets
automatically refreshed. This also lets us visualize form fields.
There's no "Action State" here for showing error messages that are not
thrown, that's still up to user space.
The "next" prerelease channel represents what will be published the next
time we do a stable release. We publish a new "next" release every day
using a timed CI workflow.
When we introduced this prerelease channel a few years ago, another name
we considered was "canary". But I proposed "next" instead to create a
greater distinction between this channel and the "experimental" channel
(which is published at the same cadence, but includes extra experimental
features), because some other projects use "canary" to refer to releases
that are more unstable than how we would use it.
The main downside of "next" is someone might mistakenly assume the name
refers to Next.js. We were aware of this risk at the time but didn't
think it would be an issue in practice.
However, colloquially, we've ended up referring to this as the "canary"
channel anyway to avoid precisely that confusion.
So after further discussion, we've agreed to rename to "canary".
This affects the label used in the version string (e.g.
`18.3.0-next-a1c2d3e4` becomes `18.3.0-canary-a1c2d3e4`) as well as the
npm dist tags used to publish the releases. For now, I've chosen to
publish the canaries using both `@canary` and `@next` dist tags, so that
downstream consumers who might depend on `@next` have time to adjust. We
can remove that later after the change has been communicated.
Stacked on top of #26735.
This allows a framework to add a `$$FORM_ACTION` property to a function.
This lets the framework return a set of props to use in place of the
function but only during SSR. Effectively, this lets you implement
progressive enhancement of form actions using some other way instead of
relying on the replay feature.
This will be used by RSC on Server References automatically by
convention in a follow up, but this mechanism can also be used by other
frameworks/libraries.
This adds an experimental hook tentatively called useOptimisticState.
(The actual name needs some bikeshedding.)
The headline feature is that you can use it to implement optimistic
updates. If you set some optimistic state during a transition/action,
the state will be automatically reverted once the transition completes.
Another feature is that the optimistic updates will be continually
rebased on top of the latest state.
It's easiest to explain with examples; we'll publish documentation as
the API gets closer to stabilizing. See tests for now.
Technically the use cases for this hook are broader than just optimistic
updates; you could use it implement any sort of "pending" state, such as
the ones exposed by useTransition and useFormStatus. But we expect
people will most often reach for this hook to implement the optimistic
update pattern; simpler cases are covered by those other hooks.
This test started failing recently in older versions of React because
the Scheduler priority inside a microtask is Normal instead of
Immediate. This is expected because microtasks are not Scheduler tasks;
it's an implementation detail.
I gated the test to only run in v17 because it's a regression test for
legacy Suspense behavior, and the implementation details of the snapshot
changed in v18.
Test plan
---------
Using latest:
```
yarn test --build --project devtools --release-channel=experimental profilingcache
```
Using v17 (typically runs in a timed CI workflow):
```
/scripts/circleci/download_devtools_regression_build.js 17.0 --replaceBuild
yarn test --build --project devtools --release-channel=experimental --reactVersion 17.0 profilingcache
```
When there are multiple async actions at the same time, we entangle them
together because we can't be sure which action an update might be
associated with. (For this, we'd need AsyncContext.) However, if one of
the async actions fails with an error, it should only affect that
action, not all the other actions it may be entangled with.
Resolving each action independently also means they can have independent
pending state types, rather than being limited to an `isPending`
boolean. We'll use this to implement an upcoming form API.
## Summary
We added some post-processing in the build for RN in #26616 that broke
for users on Windows due to how line endings were handled to the regular
expression to insert some directives in the docblock. This fixes that
problem, reported in #26697 as well.
## How did you test this change?
Verified files are still built correctly on Mac/Linux. Will ask for help
to test on Windows.
We used to have Event Replaying for any kind of Discrete event where
we'd track any event after hydrateRoot and before the async code/data
has loaded in to hydrate the target. However, this didn't really work
out because code inside event handlers are expected to be able to
synchronously read the state of the world at the time they're invoked.
If we replay discrete events later, the mutable state around them like
selection or form state etc. may have changed.
This limitation doesn't apply to Client Actions:
- They're expected to be async functions that themselves work
asynchronously. They're conceptually also in the "navigation" events
that happen after the "submit" events so they're already not
synchronously even before the first `await`.
- They're expected to operate mostly on the FormData as input which we
can snapshot at the time of the event.
This PR adds a bit of inline script to the Fizz runtime (or external
runtime) to track any early submit events on the page - but only if the
action URL is our placeholder `javascript:` URL. We track a queue of
these on `document.$$reactFormReplay`. Then we replay them in order as
they get hydrated and we get a handle on the Client Action function.
I add the runtime to the `bootstrapScripts` phase in Fizz which is
really technically a little too late, because on a large page, it might
take a while to get to that script even if you have displayed the form.
However, that's also true for external runtime. So there's a very short
window we might miss an event but it's good enough and better than
risking blocking display on this script.
The main thing that makes the replaying difficult to reason about is
that we can have multiple instance of React using this same queue. This
would be very usual but you could have two different Reacts SSR:ing
different parts of the tree and using around the same version. We don't
have any coordinating ids for this. We could stash something on the form
perhaps but given our current structure it's more difficult to get to
the form instance in the commit phase and a naive solution wouldn't
preserve ordering between forms.
This solution isn't 100% guaranteed to preserve ordering between
different React instances neither but should be in order within one
instance which is the common case.
The hard part is that we don't know what instance something will belong
to until it hydrates. So to solve that I keep everything in the original
queue while we wait, so that ordering is preserved until we know which
instance it'll go into. I ended up doing a bunch of clever tricks to
make this work. These could use a lot more tests than I have right now.
Another thing that's tricky is that you can update the action before
it's replayed but we actually want to invoke the old action if that
happens. So we have to extract it even if we can't invoke it right now
just so we get the one that was there during hydration.
We currently use rollup to make an adhoc bundle from the file system
when we're testing an import of an external file.
This doesn't follow all the interception rules that we use in jest and
in our actual builds.
This switches to just using jest require() to load these. This means
that they effectively have to load into the global document so this only
works with global document tests which is all we have now anyway.
Stacked on #26557
Supporting Float methods such as ReactDOM.preload() are challenging for
flight because it does not have an easy means to convey direct
executions in other environments. Because the flight wire format is a
JSON-like serialization that is expected to be rendered it currently
only describes renderable elements. We need a way to convey a function
invocation that gets run in the context of the client environment
whether that is Fizz or Fiber.
Fiber is somewhat straightforward because the HostDispatcher is always
active and we can just have the FlightClient dispatch the serialized
directive.
Fizz is much more challenging becaue the dispatcher is always scoped but
the specific request the dispatch belongs to is not readily available.
Environments that support AsyncLocalStorage (or in the future
AsyncContext) we will use this to be able to resolve directives in Fizz
to the appropriate Request. For other environments directives will be
elided. Right now this is pragmatic and non-breaking because all
directives are opportunistic and non-critical. If this changes in the
future we will need to reconsider how widespread support for async
context tracking is.
For Flight, if AsyncLocalStorage is available Float methods can be
called before and after await points and be expected to work. If
AsyncLocalStorage is not available float methods called in the sync
phase of a component render will be captured but anything after an await
point will be a noop. If a float call is dropped in this manner a DEV
warning should help you realize your code may need to be modified.
This PR also introduces a way for resources (Fizz) and hints (Flight) to
flush even if there is not active task being worked on. This will help
when Float methods are called in between async points within a function
execution but the task is blocked on the entire function finishing.
This PR also introduces deduping of Hints in Flight using the same
resource keys used in Fizz. This will help shrink payload sizes when the
same hint is attempted to emit over and over again
This is the next step toward full support for async form actions.
Errors thrown inside form actions should cause the form to re-render and
throw the error so it can be captured by an error boundary. The behavior
is the same if the `<form />` had an internal useTransition hook, which
is pretty much exactly how we implement it, too.
The first time an action is called, the form's HostComponent is
"upgraded" to become stateful, by lazily mounting a list of hooks. The
rest of the implementation for function components can be shared.
Because the error handling behavior added in this commit is just using
useTransition under-the-hood, it also handles pending states, too.
However, this pending state can't be observed until we add a new hook
for that purpose. I'll add this next.
This puts the change introduced by #26611 behind a flag until Meta is
able to roll it out. Disabling the flag reverts back to the old
behavior, where retries are throttled if there's still data remaining in
the tree, but not if all the data has finished loading.
The new behavior is still enabled in the public builds.
- substr is Annex B
- substring silently flips its arguments if they're in the "wrong order", which is confusing
- slice is better than sliced bread (no pun intended) and also it works the same way on Arrays so there's less to remember
---
> I'd be down to just lint and enforce a single form just for the potential compression savings by using a repeated string.
_Originally posted by @sebmarkbage in https://github.com/facebook/react/pull/26663#discussion_r1170455401_
Some minor changes, observed while working on 24.7.5 release:
- Updated numeration of text instructions
- `reactjs.org` -> `react.dev`
- Fixed using `npm view` command for node 16+, `publish-release` script
currently fails if used with node 16+
We have moved away from HostConfig since the name does not fully
describe the configs we customize per runtime like FlightClient,
FlightServer, Fizz, and Fiber. This commit generalizes $$$hostconfig to
$$$config
part of https://github.com/facebook/react/pull/26571
merging separately to improve tracking of files renames in git
Rename HostConfig files to FiberConfig to clarify they are configs for
Fiber and not Fizz/Flight. This better conforms to the naming used in
Flight and now Fizz of `ReactFlightServerConfig` and `ReactFizzConfig`
`act` uses the `didScheduleLegacyUpdate` field to simulate the behavior
of batching in React <17 and below. It's a quirk leftover from a
previous implementation, not intentionally designed.
This sets `didScheduleLegacyUpdate` every time a legacy root receives an
update as opposed to only when the `executionContext` is empty. There's
no real reason to do it this way over some other way except that it's
how it used to work before #26512 and we should try our best to maintain
the existing behavior, quirks and all, since existing tests may have
come to accidentally rely on it.
This should fix some (though not all) of the internal Meta tests that
started failing after #26512 landed.
Will add a regression test before merging.
## Summary
This adds the ability to create public instances for text nodes in
Fabric. The implementation for the public instances lives in React
Native (as it does for host components after #26437). The logic here
just handles their lazy instantiation when requested via
`getPublicInstanceFromInternalInstanceHandle`, which is called by Fabric
with information coming from the shadow tree.
It's important that the creation of public instances for text nodes is
done lazily to avoid regressing memory usage when unused. Instances for
text nodes are left intact if the public instance is never accessed.
This is necessary to implement access to text nodes in React Native as
explained in
https://github.com/react-native-community/discussions-and-proposals/pull/607
## How did you test this change?
Added unit tests (also fixed a test that was only testing the logic in a
mock :S).
When React receives new input (via `setState`, a Suspense promise
resolution, and so on), it needs to ensure there's a rendering task
associated with the update. Most of this happens
`ensureRootIsScheduled`.
If a single event contains multiple updates, we end up running the
scheduling code once per update. But this is wasteful because we really
only need to run it once, at the end of the event (or in the case of
flushSync, at the end of the scope function's execution).
So this PR moves the scheduling logic to happen in a microtask instead.
In some cases, we will force it run earlier than that, like for
`flushSync`, but since updates are batched by default, it will almost
always happen in the microtask. Even for discrete updates.
In production, this should have no observable behavior difference. In a
testing environment that uses `act`, this should also not have a
behavior difference because React will push these tasks to an internal
`act` queue.
However, tests that do not use `act` and do not simulate an actual
production environment (like an e2e test) may be affected. For example,
before this change, if a test were to call `setState` outside of `act`
and then immediately call `jest.runAllTimers()`, the update would be
synchronously applied. After this change, that will no longer work
because the rendering task (a timer, in this case) isn't scheduled until
after the microtask queue has run.
I don't expect this to be an issue in practice because most people do
not write their tests this way. They either use `act`, or they write
e2e-style tests.
The biggest exception has been... our own internal test suite. Until
recently, many of our tests were written in a way that accidentally
relied on the updates being scheduled synchronously. Over the past few
weeks, @tyao1 and I have gradually converted the test suite to use a new
set of testing helpers that are resilient to this implementation detail.
(There are also some old Relay tests that were written in the style of
React's internal test suite. Those will need to be fixed, too.)
The larger motivation behind this change, aside from a minor performance
improvement, is we intend to use this new microtask to perform
additional logic that doesn't yet exist. Like inferring the priority of
a custom event.
