This shows the title in the top corner of the rect if there's enough
space.
The complex bit here is that it can be noisy if too many boundaries
occupy the same space to overlap or partially overlap.
This uses an R-tree to store all the rects to find overlapping
boundaries to cut the available space to draw inside the rect. We use
this to compute the rectangle within the rect which doesn't have any
overlapping boundaries.
The roots don't count as overlapping. Similarly, a parent rect is not
consider overlapping a child. However, if two sibling boundaries occupy
the same space, no title will be drawn.
<img width="734" height="813" alt="Screenshot 2025-10-19 at 5 34 49 PM"
src="https://github.com/user-attachments/assets/2b848b9c-3b78-48e5-9476-dd59a7baf6bf"
/>
We might also consider drawing the "Initial Paint" title at the root but
that's less interesting. It's interesting in the beginning before you
know about the special case at the root but after that it's just always
the same value so just adds noise.
Added the standard Meta Platforms, Inc. MIT license notice to the top of
the feature flag comparison script to ensure compliance with repository
licensing requirements and for code consistency.
**No functional or logic changes were made to the code.**
## Summary
When upgrading to `babel-plugin-react-compiler@1.0.0` in a project that
uses `zod@3` we are running into TypeScript errors like:
```
node_modules/babel-plugin-react-compiler/dist/index.d.ts:435:10 - error TS2694: Namespace '"/REDACTED/node_modules/zod/v3/external"' has no exported member 'core'.
435 }, z.core.$strip>>>;
~~~~
```
This problem seems to be related to
d6eb735938, which introduced zod v3/v4
compatibility. Since `zod` is bundled into the compiler source this does
not cause runtime issues and only manifests as TypeScript errors. My
proposed solution is this PR is to use zod's [subpath versioning
strategy](https://zod.dev/v4/versioning?id=versioning-in-zod-4) which
allows you to support v3 and v4 APIs on both major versions.
Changes in this PR include:
- Updated `zod` import paths to `zod/v4`
- Bumped min `zod` version to `^3.25.0` for zod which guarantees the
`zod/v4` subpath is available.
- Updated `zod-validation-error` import paths to
`zod-validation-error/v4`
- Bumped min `zod-validation-error ` version to `^3.5.0`
- Updated `externals` tsup configuration where appropriate.
Once the compiler drops zod v3 support we could optionally remove the
`/v4` subpath from the imports.
## How did you test this change?
Not totally sure the best way to test. I ran `NODE_ENV=production yarn
workspace babel-plugin-react-compiler run build --dts` and diffed the
`dist/` folder between my change and `v1.0.0` and it looks correct. We
have a `patch-package` patch to workaround this for now and it works as
expected.
```diff
diff --git a/node_modules/babel-plugin-react-compiler/dist/index.d.ts b/node_modules/babel-plugin-react-compiler/dist/index.d.ts
index 81c3f3d..daafc2c 100644
--- a/node_modules/babel-plugin-react-compiler/dist/index.d.ts
+++ b/node_modules/babel-plugin-react-compiler/dist/index.d.ts
@@ -1,7 +1,7 @@
import * as BabelCore from '@babel/core';
import { NodePath as NodePath$1 } from '@babel/core';
import * as t from '@babel/types';
-import { z } from 'zod';
+import { z } from 'zod/v4';
import { NodePath, Scope } from '@babel/traverse';
interface Result<T, E> {
```
Co-authored-by: Henry Q. Dineen <henryqdineen@gmail.com>
## Overview
This PR adds the `ref` prop to `<Fragment>` in `react@canary`.
This means this API is ready for final feedback and prepared for a
semver stable release.
## What this means
Shipping Fragment refs to canary means they have gone through extensive
testing in production, we are confident in the stability of the APIs,
and we are preparing to release it in a future semver stable version.
Libraries and frameworks following the [Canary
Workflow](https://react.dev/blog/2023/05/03/react-canaries) should begin
implementing and testing these features.
## Why we follow the Canary Workflow
To prepare for semver stable, libraries should test canary features like
Fragment refs with `react@canary` to confirm compatibility and prepare
for the next semver release in a myriad of environments and
configurations used throughout the React ecosystem. This provides
libraries with ample time to catch any issues we missed before slamming
them with problems in the wider semver release.
Since these features have already gone through extensive production
testing, and we are confident they are stable, frameworks following the
[Canary Workflow](https://react.dev/blog/2023/05/03/react-canaries) can
also begin adopting canary features like Fragment refs.
This adoption is similar to how different Browsers implement new
proposed browser features before they are added to the standard. If a
frameworks adopts a canary feature, they are committing to stability for
their users by ensuring any API changes before a semver stable release
are opaque and non-breaking to their users.
Apps not using a framework are also free to adopt canary features like
Fragment refs as long as they follow the [Canary
Workflow](https://react.dev/blog/2023/05/03/react-canaries), but we
generally recommend waiting for a semver stable release unless you have
the capacity to commit to following along with the canary changes and
debugging library compatibility issues.
Waiting for semver stable means you're able to benefit from libraries
testing and confirming support, and use semver as signal for which
version of a library you can use with support of the feature.
## Docs
Check out the ["React Labs: View Transitions, Activity, and
more"](https://react.dev/blog/2025/04/23/react-labs-view-transitions-activity-and-more#fragment-refs)
blog post, and [the new docs for Fragment
refs`](https://react.dev/reference/react/Fragment#fragmentinstance) for
more info.
This was merged into the 19.1.1 patch release branch in
https://github.com/facebook/react/pull/33972 but we never upstreamed it
to main. This should merge to main to make it easier to sync versions to
RN after future releases.
---------
Co-authored-by: Riccardo Cipolleschi <cipolleschi@meta.com>
Triggering the "(Runtime) Publish Prereleases Manual" workflow with a
short git sha doesn't work. It needs the full sha. We might be able to
make it work with the short sha as well, but for now we can at least
document the restriction.
## Overview
This PR ships `<Activity />` to the `react@canary` release channel for
final feedback and prepare for semver stable release.
## What this means
Shipping `<Activity />` to canary means it has gone through extensive
testing in production, we are confident in the stability of the feature,
and we are preparing to release it in a future semver stable version.
Libraries and frameworks following the [Canary
Workflow](https://react.dev/blog/2023/05/03/react-canaries) should begin
implementing and testing the feature.
## Why we follow the Canary Workflow
To prepare for semver stable, libraries should test canary features like
`<Activity>` with `react@canary` to confirm compatibility and prepare
for the next semver release in a myriad of environments and
configurations used throughout the React ecosystem. This provides
libraries with ample time to catch any issues we missed before slamming
them with problems in the wider semver release.
Since these features have already gone through extensive production
testing, and we are confident they are stable, frameworks following the
[Canary Workflow](https://react.dev/blog/2023/05/03/react-canaries) can
also begin adopting canary features like `<Activity />`.
This adoption is similar to how different Browsers implement new
proposed browser features before they are added to the standard. If a
frameworks adopts a canary feature, they are committing to stability for
their users by ensuring any API changes before a semver stable release
are opaque and non-breaking to their users.
Apps not using a framework are also free to adopt canary features like
Activity as long as they follow the [Canary
Workflow](https://react.dev/blog/2023/05/03/react-canaries), but we
generally recommend waiting for a semver stable release unless you have
the capacity to commit to following along with the canary changes and
debugging library compatibility issues.
Waiting for semver stable means you're able to benefit from libraries
testing and confirming support, and use semver as signal for which
version of a library you can use with support of the feature.
## Docs
Check out the ["React Labs: View Transitions, Activity, and
more"](https://react.dev/blog/2025/04/23/react-labs-view-transitions-activity-and-more#activity)
blog post, and [the new docs for
`<Activity>`](https://react.dev/reference/react/Activity) for more info.
## TODO
- [x] Bump Activity docs to Canary
https://github.com/reactjs/react.dev/pull/7974
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
This adds `experimental_scrollIntoView(alignToTop)`. It doesn't yet
support `scrollIntoView(options)`.
Cases:
- No host children: Without host children, we represent the virtual
space of the Fragment by attempting to scroll to the nearest edge by
using its siblings. If the preferred sibling is not found, we'll try the
other side, and then the parent.
- 1 or more host children: In order to handle the case of children
spread between multiple scroll containers, we scroll to each child in
reverse order based on the `alignToTop` flag.
Due to the complexity of multiple scroll containers and dealing with
portals, I've added this under a separate feature flag with an
experimental prefix. We may stabilize it along with the other APIs, but
this allows us to not block the whole feature on it.
This PR was previously implementing a much more complex approach to
handling multiple scroll containers and portals. We're going to start
with the simple loop and see if we can find any concrete use cases where
that doesn't suffice. 01f31d43013ba7f6f54fd8a36990bbafc3c3cc68 is the
diff between approaches here.
This is the last version before "Natural Inference" change to Flow that
will require more changes, so doing a quick fast-forward PR here.
- Disabled a new Flow lint against unsafe `Object.assign`.
NOTE: this is a merged version of @mofeiZ's original PR along with my
edits per offline discussion. The description is updated to reflect the
latest approach.
The key problem we're trying to solve with this PR is to allow
developers more control over the compiler's various validations. The
idea is to have a number of rules targeting a specific category of
issues, such as enforcing immutability of props/state/etc or disallowing
access to refs during render. We don't want to have to run the compiler
again for every single rule, though, so @mofeiZ added an LRU cache that
caches the full compilation output of N most recent files. The first
rule to run on a given file will cause it to get cached, and then
subsequent rules can pull from the cache, with each rule filtering down
to its specific category of errors.
For the categories, I went through and assigned a category roughly 1:1
to existing validations, and then used my judgement on some places that
felt distinct enough to warrant a separate error. Every error in the
compiler now has to supply both a severity (for legacy reasons) and a
category (for ESLint). Each category corresponds 1:1 to a ESLint rule
definition, so that the set of rules is automatically populated based on
the defined categories.
Categories include a flag for whether they should be in the recommended
set or not.
Note that as with the original version of this PR, only
eslint-plugin-react-compiler is changed. We still have to update the
main lint rule.
## Test Plan
* Created a sample project using ESLint v9 and verified that the plugin
can be configured correctly and detects errors
* Edited `fixtures/eslint-v9` and introduced errors, verified that the w
latest config changes in that fixture it correctly detects the errors
* In the sample project, confirmed that the LRU caching is correctly
caching compiler output, ie compiling files just once.
Co-authored-by: Mofei Zhang <feifei0@meta.com>
This adds a "suspended by" row for each chunk that is referenced from a
client reference. So when you select a client component, you can see
what bundles will block that client component when loading on the
client.
This is only done in the browser build since if we added it on the
server, it would show up as a blocking resource and while it's possible
we expect that a typical server request won't block on loading JS.
<img width="664" height="486" alt="Screenshot 2025-08-17 at 3 45 14 PM"
src="https://github.com/user-attachments/assets/b1f83445-2a4e-4470-9a20-7cd215ab0482"
/>
<img width="745" height="678" alt="Screenshot 2025-08-17 at 3 46 58 PM"
src="https://github.com/user-attachments/assets/3558eae1-cf34-4e11-9d0e-02ec076356a4"
/>
Currently this is only included if it ends up wrapped in a lazy like in
the typical type position of a Client Component, but there's a general
issue that maybe hard references need to transfer their debug info to
the parent which can transfer it to the Fiber.
## Summary
ReactNativeAttributePayloadFabric was synced to react-native in
0e42d33cbc.
We should now consume these methods from the
ReactNativePrivateInterface.
Moving these methods to the React Native repo gives us more flexibility
to experiment with new techniques for bridging and diffing props
payloads.
I did have to leave some stub implementations for existing unit tests,
but moved all detailed tests to the React Native repo.
## How did you test this change?
* `yarn prettier`
* `yarn test ReactFabric-test`
This adds plumbing for opening a stream from the Flight Client to the
Flight Server so it can ask for more data on-demand. In this mode, the
Flight Server keeps the connection open as long as the client is still
alive and there's more objects to load. It retains any depth limited
objects so that they can be asked for later. In this first PR it just
releases the object when it's discovered on the server and doesn't
actually lazy load it yet. That's coming in a follow up.
This strategy is built on the model that each request has its own
channel for this. Instead of some global registry. That ensures that
referential identity is preserved within a Request and the Request can
refer to previously written objects by reference.
The fixture implements a WebSocket per request but it doesn't have to be
done that way. It can be multiplexed through an existing WebSocket for
example. The current protocol is just a Readable(Stream) on the server
and WritableStream on the client. It could even be sent through a HTTP
request body if browsers implemented full duplex (which they don't).
This PR only implements the direction of messages from Client to Server.
However, I also plan on adding Debug Channel in the other direction to
allow debug info (optionally) be sent from Server to Client through this
channel instead of through the main RSC request. So the `debugChannel`
option will be able to take writable or readable or both.
---------
Co-authored-by: Hendrik Liebau <mail@hendrik-liebau.de>
This was really meant to be there from the beginning. A `cache()`:ed
entry has a life time. On the server this ends when the render finishes.
On the client this ends when the cache of that scope gets refreshed.
When a cache is no longer needed, it should be possible to abort any
outstanding network requests or other resources. That's what
`cacheSignal()` gives you. It returns an `AbortSignal` which aborts when
the cache lifetime is done based on the same execution scope as a
`cache()`ed function - i.e. `AsyncLocalStorage` on the server or the
render scope on the client.
```js
import {cacheSignal} from 'react';
async function Component() {
await fetch(url, { signal: cacheSignal() });
}
```
For `fetch` in particular, a patch should really just do this
automatically for you. But it's useful for other resources like database
connections.
Another reason it's useful to have a `cacheSignal()` is to ignore any
errors that might have triggered from the act of being aborted. This is
just a general useful JavaScript pattern if you have access to a signal:
```js
async function getData(id, signal) {
try {
await queryDatabase(id, { signal });
} catch (x) {
if (!signal.aborted) {
logError(x); // only log if it's a real error and not due to cancellation
}
return null;
}
}
```
This just gets you a convenient way to get to it without drilling
through so a more idiomatic code in React might look something like.
```js
import {cacheSignal} from "react";
async function getData(id) {
try {
await queryDatabase(id);
} catch (x) {
if (!cacheSignal()?.aborted) {
logError(x);
}
return null;
}
}
```
If it's called outside of a React render, we normally treat any cached
functions as uncached. They're not an error call. They can still load
data. It's just not cached. This is not like an aborted signal because
then you couldn't issue any requests. It's also not like an infinite
abort signal because it's not actually cached forever. Therefore,
`cacheSignal()` returns `null` when called outside of a React render
scope.
Notably the `signal` option passed to `renderToReadableStream` in both
SSR (Fizz) and RSC (Flight Server) is not the same instance that comes
out of `cacheSignal()`. If you abort the `signal` passed in, then the
`cacheSignal()` is also aborted with the same reason. However, the
`cacheSignal()` can also get aborted if the render completes
successfully or fatally errors during render - allowing any outstanding
work that wasn't used to clean up. In the future we might also expand on
this to give different
[`TaskSignal`](https://developer.mozilla.org/en-US/docs/Web/API/TaskSignal)
to different scopes to pass different render or network priorities.
On the client version of `"react"` this exposes a noop (both for
Fiber/Fizz) due to `disableClientCache` flag but it's exposed so that
you can write shared code.
Stacked on #33482.
There's a flaw with getting information from the execution context of
the ping. For the soft-deprecated "throw a promise" technique, this is a
bit unreliable because you could in theory throw the same one multiple
times. Similarly, a more fundamental flaw with that API is that it
doesn't allow for tracking the information of Promises that are already
synchronously able to resolve.
This stops tracking the async debug info in the case of throwing a
Promise and only when you render a Promise. That means some loss of data
but we should just warn for throwing a Promise anyway.
Instead, this also adds support for tracking `use()`d thenables and
forwarding `_debugInfo` from then. This is done by extracting the info
from the Promise after the fact instead of in the resolve so that it
only happens once at the end after the pings are done.
This also supports passing the same Promise in multiple places and
tracking the debug info at each location, even if it was already
instrumented with a synchronous value by the time of the second use.
This effectively lets us consume Web Streams in a Node build. In fact
the Node entry point is now just adding Node stream APIs.
For the client, this is simple because the configs are not actually
stream type specific. The server is a little trickier.
Reverts #33457, #33456 and #33442.
There are too many issues with wrappers, lazy init, stateful modules,
duplicate instantiation of async_hooks and duplication of code.
Instead, we'll just do a wrapper polyfill that uses Node Streams
internally.
I kept the client indirection files that I added for consistency with
the server though.
Follow up to #33442. This is the bundled version.
To keep type check passes from exploding and the maintainance of the
annoying `paths: []` list small, this doesn't add this to flow type
checks. We might miss some config but every combination should already
be covered by other one passes.
I also don't add any jest tests because to test these double export
entry points we need conditional importing to cover builds and
non-builds which turns out to be difficult for the Flight builds so
these aren't covered by any basic build tests.
This approach is what I'm going for, for the other bundlers too.
We want to make sure that we can block the reveal of a well designed
complete shell reliably. In the Suspense model, client transitions don't
have any way to implicitly resolve. This means you need to use Suspense
or SuspenseList to explicitly split the document. Relying on implicit
would mean you can't add a Suspense boundary later where needed. So we
highly encourage the use of them around large content.
However, if you have constructed a too large shell (e.g. by not adding
any Suspense boundaries at all) then that might take too long to render
on the client. We shouldn't punish users (or overzealous metrics
tracking tools like search engines) in that scenario.
This opts out of render blocking if the shell ends up too large to be
intentional and too slow to load. Instead it deopts to showing the
content split up in arbitrary ways (browser default). It only does this
for SSR, and not client navs so it's not reliable.
In fact, we issue an error to `onError`. This error is recoverable in
that the document is still produced. It's up to your framework to decide
if this errors the build or just surface it for action later.
What should be the limit though? There's a trade off here. If this limit
is too low then you can't fit a reasonably well built UI within it
without getting errors. If it's too high then things that accidentally
fall below it might take too long to load.
I came up with 512kB of uncompressed shell HTML. See the comment in code
for the rationale for this number. TL;DR: Data and theory indicates that
having this much content inside `rel="expect"` doesn't meaningfully
change metrics. Research of above-the-fold content on various websites
indicate that this can comfortable fit all of them which should be
enough for any intentional initial paint.
We highly recommend using Node Streams in Node.js because it's much
faster and it is less likely to cause issues when chained in things like
compression algorithms that need explicit flushing which the Web Streams
ecosystem doesn't have a good solution for. However, that said, people
want to be able to use the worse option for various reasons.
The `.edge` builds aren't technically intended for Node.js. A Node.js
environments needs to be patched in various ways to support it. It's
also less optimal since it can't use [Node.js exclusive
features](https://github.com/facebook/react/pull/33388) and have to use
[the lowest common
denominator](https://github.com/facebook/react/pull/27399) such as JS
implementations instead of native.
This adds a Web Streams build of Fizz but exclusively for Node.js so
that in it we can rely on Node.js modules. The main difference compared
to Edge is that SSR now uses `createHash` from the `"crypto"` module and
imports `TextEncoder` from `"util"`. We use `setImmediate` instead of
`setTimeout`.
The public API is just `react-dom/server` which in Node.js automatically
imports `react-dom/server.node` which re-exports the legacy bundle, Node
Streams bundle and Node Web Streams bundle. The main downside is if your
bundler isn't smart to DCE this barrel file.
With Flight the difference is larger but that's a bigger lift.
Stacked on #33403.
When a Promise is coming from React such as when it's passed from
another environment, we should forward the debug information from that
environment. We already do that when rendered as a child.
This makes it possible to also `await promise` and have the information
from that instrumented promise carry through to the next render.
This is a bit tricky because the current protocol is that we have to
read it from the Promise after it resolves so it has time to be assigned
to the promise. `async_hooks` doesn't pass us the instance (even though
it has it) when it gets resolved so we need to keep it around. However,
we have to be very careful because if we get this wrong it'll cause a
memory leak since we retain things by `asyncId` and then manually listen
for `destroy()` which can only be called once a Promise is GC:ed, which
it can't be if we retain it. We have to therefore use a `WeakRef` in
case it never resolves, and then read the `_debugInfo` when it resolves.
We could maybe install a setter or something instead but that's also
heavy.
The other issues is that we don't use native Promises in
ReactFlightClient so our instrumented promises aren't picked up by the
`async_hooks` implementation and so we never get a handle to our
thenable instance. To solve this we can create a native wrapper only in
DEV.
This lets us track what data each Server Component depended on. This
will be used by Performance Track and React DevTools.
We use Node.js `async_hooks`. This has a number of downside. It is
Node.js specific so this feature is not available in other runtimes
until something equivalent becomes available. It's [discouraged by
Node.js docs](https://nodejs.org/api/async_hooks.html#async-hooks). It's
also slow which makes this approach only really viable in development
mode. At least with stack traces. However, it's really the only solution
that gives us the data that we need.
The [Diagnostic
Channel](https://nodejs.org/api/diagnostics_channel.html) API is not
sufficient. Not only is many Node.js built-in APIs missing but all
libraries like databases are also missing. Were as `async_hooks` covers
pretty much anything async in the Node.js ecosystem.
However, even if coverage was wider it's not actually showing the
information we want. It's not enough to show the low level I/O that is
happening because that doesn't provide the context. We need the stack
trace in user space code where it was initiated and where it was
awaited. It's also not each low level socket operation that we want to
surface but some higher level concept which can span a sequence of I/O
operations but as far as user space is concerned.
Therefore this solution is anchored on stack traces and ignore listing
to determine what the interesting span is. It is somewhat
Promise-centric (and in particular async/await) because it allows us to
model an abstract span instead of just random I/O. Async/await points
are also especially useful because this allows Async Stacks to show the
full sequence which is not supported by random callbacks. However, if no
Promises are involved we still to our best to show the stack causing
plain I/O callbacks.
Additionally, we don't want to track all possible I/O. For example,
side-effects like logging that doesn't affect the rendering performance
doesn't need to be included. We only want to include things that
actually block the rendering output. We also need to track which data
blocks each component so that we can track which data caused a
particular subtree to suspend.
We can do this using `async_hooks` because we can track the graph of
what resolved what and then spawned what.
To track what suspended what, something has to resolve. Therefore it
needs to run to completion before we can show what it was suspended on.
So something that never resolves, won't be tracked for example.
We use the `async_hooks` in `ReactFlightServerConfigDebugNode` to build
up an `ReactFlightAsyncSequence` graph that collects the stack traces
for basically all I/O and Promises allocated in the whole app. This is
pretty heavy, especially the stack traces, but it's because we don't
know which ones we'll need until they resolve. We don't materialize the
stacks until we need them though.
Once they end up pinging the Flight runtime, we collect which current
executing task that pinged the runtime and then log the sequence that
led up until that runtime into the RSC protocol. Currently we only
include things that weren't already resolved before we started rendering
this task/component, so that we don't log the entire history each time.
Each operation is split into two parts. First a `ReactIOInfo` which
represents an I/O operation and its start/end time. Basically the start
point where it was start. This is basically represents where you called
`new Promise()` or when entering an `async function` which has an
implied Promise. It can be started in a different component than where
it's awaited and it can be awaited in multiple places. Therefore this is
global information and not associated with a specific Component.
The second part is `ReactAsyncInfo`. This represents where this I/O was
`await`:ed or `.then()` called. This is associated with a point in the
tree (usually the Promise that's a direct child of a Component). Since
you can have multiple different I/O awaited in a sequence technically it
forms a dependency graph but to simplify the model these awaits as
flattened into the `ReactDebugInfo` list. Basically it contains each
await in a sequence that affected this part from unblocking.
This means that the same `ReactAsyncInfo` can appear in mutliple
components if they all await the same `ReactIOInfo` but the same Promise
only appears once.
Promises that are only resolved by other Promises or immediately are not
considered here. Only if they're resolved by an I/O operation. We pick
the Promise basically on the border between user space code and ignored
listed code (`node_modules`) to pick the most specific span but abstract
enough to not give too much detail irrelevant to the current audience.
Similarly, the deepest `await` in user space is marked as the relevant
`await` point.
This feature is only available in the `node` builds of React. Not if you
use the `edge` builds inside of Node.js.
---------
Co-authored-by: Sebastian "Sebbie" Silbermann <silbermann.sebastian@gmail.com>
## Summary
This tool leverages DevTools to get the component tree from the
currently open React App. This gives realtime information to agents
about the state of the app.
## How did you test this change?
Tested integration with Claude Desktop
This uses the richer `serverAct` helper that we already use in other
tests.
This avoids using the `Scheduler`. We don't use that package on the
server so it doesn't make sense to simulate going through it.
Additionally, we really should be getting rid of it on the client too to
favor `postTask` polyfills.
We have many cases internally where the `containerInstance` resolves to
a comment node. `restoreRootViewTransitionName` is called when
`enableViewTransition` is on, even without introducing a
`<ViewTransition />`. So that means it can crash pages because
`containerInstance.style` is `undefined` just by turning on the flag.
This skips cancel/restore of root view transition name if a comment node is the root.
When needed.
For the external runtime we always include this wrapper.
For others, we only include it if we have an ViewTransitions affecting.
If we discover the ViewTransitions late, then we can upgrade an already
emitted instruction.
This doesn't yet do anything useful with it, that's coming in a follow
up. This is just the mechanism for how it gets installed.
Stacked on #33160.
By default, if `onDefaultTransitionIndicator` is not overridden, this
will trigger a fake Navigation event using the Navigation API. This is
intercepted to create an on-going navigation until we complete the
Transition. Basically each default Transition is simulated as a
Navigation.
This triggers the native browser loading state (in Chrome at least). So
now by default the browser spinner spins during a Transition if no other
loading state is provided. Firefox and Safari hasn't shipped Navigation
API yet and even in the flag Safari has, it doesn't actually trigger the
native loading state.
To ensures that you can still use other Navigations concurrently, we
don't start our fake Navigation if there's one on-going already.
Similarly if our fake Navigation gets interrupted by another. We wait
for on-going ones to finish and then start a new fake one if we're
supposed to be still pending.
There might be other routers on the page that might listen to intercept
Navigation Events. Typically you'd expect them not to trigger a refetch
when navigating to the same state. However, if they want to detect this
we provide the `"react-transition"` string in the `info` field for this
purpose.
Stacked on #33073.
React semantics is that Suspense boundaries reveal with a throttle
(300ms). That helps avoid flashing reveals when a stream reveals many
individual steps back to back. It can also improve overall performance
by batching the layout and paint work that has to happen at each step.
Unfortunately we never implemented this for SSR streaming - only for
client navigations. This is highly noticeable on very dynamic sites with
lots of Suspense boundaries. It can look good with a client nav but feel
glitchy when you reload the page or initial load.
This fixes the Fizz runtime to be throttled and reveals batched into a
single paint at a time. We do this by first tracking the last paint
after the complete (this will be the first paint if `rel="expect"` is
respected). Then in the `completeBoundary` operation we queue the
operation and then flush it all into a throttled batch.
Another motivation is that View Transitions need to operate as a batch
and individual steps get queued in a sequence so it's extra important to
include as much content as possible in each animated step. This will be
done in a follow up for SSR View Transitions.
Stacked on #33065.
The runtime is about to be a lot more complicated so we need to start
sharing some more code.
The problem with sharing code is that we want the inline runtime to as
much as possible be isolated in its scope using only a few global
variables to refer across runtimes.
A problem with Closure Compiler is that it refuses to inline functions
if they have closures inside of them. Which makes sense because of how
VMs work it can cause memory leaks. However, in our cases this doesn't
matter and code size matters more. So we can't use many clever tricks.
So this just favors writing the source in the inline form. Then we add
an extra compiler pass to turn those global variables into local
variables in the external runtime.
Adds Fragment Ref support to RN through the Fabric config, starting with
`observeUsing`/`unobserveUsing`. This is mostly a copy from the
implementation on DOM, and some of it can likely be shared in the future
but keeping it separate for now and we can refactor as we add more
features.
Added a basic test with Fabric, but testing specific methods requires so
much mocking that it doesn't seem valuable here.
I built Fabric and ran on the Catalyst app internally to test with
intersection observers end to end.
