We now do a single pass over the HIR, building up two data structures:
* One tracks values that are known macro tags or macro calls.
* One tracks operands of macro-related instructions so that we can later group them.
After building up these data structures, we do a pass over the latter structure. For each macro call instruction, we recursively traverse its operands to ensure they're in the same scope. Thus, something like `fbt('hello' + fbt.param(foo(), "..."))` will correctly merge the fbt call, the `+` binary expression, the `fbt.param()` call, and `foo()` into a single scope.
We should only persist a selection once you click. Currently, we persist
the selection if you just hover which means you lose your selection
immediately when just starting to inspect. That's not what Chrome
Elements tab does - it selects on click.
I find it very frustrating that the highlight covers up the content that
I'm trying to review when stepping through the timeline. It also
triggered on keyboard navigation due to the focus which was annoying.
We could highlight something in the rects instead potentially.
In InferTypes when we infer types for properties during destructuring,
we were breaking out of the loop when we encounter a hole in the array.
Instead we should just skip that element and continue inferring later
properties.
Closes#34748
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34847).
* #34855
* __->__ #34847
This revealed that a lot of the event types were defined on the wrong
end of the bridge.
It was also a problem that events with the same name couldn't have
different arguments.
I get the wish to click the shadow but not all child boundaries are
within the bounds of the outer Suspense boundary's node.
Sometimes they overflow naturally and if we make it overflow hidden we
hide the boundaries. Maybe it would be ok if they're actually clipped by
the real DOM but right now it covers up boundaries that should be there.
Additionally, there's also a common case where the parent boundary
shrinks when suspending the children. That then causes the suspended
child boundaries to be clipped so that you can't restore them. Maybe the
virtual boundary shouldn't shrink in this case.
We can't measure Text nodes directly but we can measure a Range around
them.
This is useful since it's common, at least in examples, to use text
nodes as children of a Suspense boundary. Especially fallbacks.
We already do this in the update pass. That's what
`shouldMeasureSuspenseNode` does.
We also don't update measurements when we're inside an offscreen tree.
However, we didn't check if the boundary itself was in a suspended state
when in the `measureUnchangedSuspenseNodesRecursively` path.
This caused boundaries to disappear when their fallback didn't have a
rect (including their timeline entries).
Treat fake eval anonymous stacks as built-in. Hide built-in stack frames
unless they're used to call into a non-ignored stack frame.
The two main things to fix here is that 1) we're showing a linkified
stack for fake anonymous and 2) we're showing only built-ins when the
stack is completely internal. Meaning framework code is all noise.
Fixes https://github.com/facebook/react/issues/34770.
We need to clear measures at some point, otherwise all these copies of
props that we end up recording will allocate too much memory in
Chromium. This adds `performance.clearMeasures(...)` calls to such cases
in DEV.
Validated that entries are still shown on Performance panel timeline.
Stacked on #34829.
This lets you get an overview more easily when there's lots of things
like scripts downloading. Pluralized the name. E.g. `script` ->
`scripts` or `fetch` -> `fetches`.
This only groups them consecutively when they'd have the same place in
the list anyway because otherwise it might cover up some kind of
waterfall effects.
<img width="404" height="225" alt="Screenshot 2025-10-13 at 12 06 51 AM"
src="https://github.com/user-attachments/assets/da204a8e-d5f7-4eb0-8c51-4cc5bfd184c4"
/>
Expanded:
<img width="407" height="360" alt="Screenshot 2025-10-13 at 12 07 00 AM"
src="https://github.com/user-attachments/assets/de3c3de9-f314-4c87-b606-31bc49eb4aba"
/>
This lets you assign a name to a Promise that's passed into first party
code from third party since it otherwise would have no other stack frame
to indicate its name since the whole creation stack would be in third
party.
We already respect the `displayName` on the client but it's more
complicated on the server because we don't only consider the exact
instance passed to `use()` but the whole await sequence and we can pick
any Promise along the way for consideration. Therefore this also adds a
change where we pick the Promise node for consideration if it has a name
but no stack. Where we otherwise would've picked the I/O node.
Another thing that this PR does is treat anonymous stack frames (empty
url) as third party for purposes of heuristics like "hasUnfilteredFrame"
and the name assignment. This lets you include these in the actual
generated stacks (by overriding `filterStackFrame`) but we don't
actually want them to be considered first party code in the heuristics
since it ends up favoring those stacks and using internals like
`Function.all` in name assignment.
The index is both used as the key and for hydration purposes. Previously
we didn't preserve the index when sorting so the index didn't line up
which caused hydration to be the wrong slot when sorted.
`isStrictModeNonCompliant` on the root just means that it supports
strict mode. It's inherited by other nodes.
It's not possible to opt-in to strict mode on the root itself but rather
right below it. So we should not mark the root as being non-compliant.
This lets you select the root in the suspense tab and it shouldn't show
as red with a warning.
This ignore a Suspense boundary from the timeline when it has no visual
representation. No rect. In effect, this is not blocking the user
experience.
Technically it could be an effect that mounts which can have a
side-effect which is visible.
It could also be a meta-data tag like `<title>` which is visible. We
could hoistables a virtual representation by giving them a virtual rect.
E.g. at the top of the page. This could be added after the fact.
This ensures that we don't scroll on changes to the timeline such as
when loading a new page or while the timeline is still loading.
We only auto scroll to a boundary when we perform an explicit operation
from the user.
If an inner Offscreen commits an unhide, but an outer Offscreen is still
hidden but they're controlling the same DOM node then we shouldn't
unhide the DOM node yet.
This keeps track of whether we're directly inside a hidden offscreen. It
might be better to just do the tree search instead of keeping the stack
state since it's a rare case. Although this hide/unhide path does
trigger a lot of times even when there's no change.
This was technically a bug with Suspense too but it doesn't appear
because a suspended Suspense boundary never commits its partial state.
If it did, it would trigger this same path. But it can happen with an
outer Activity and inner Suspense.
When a debug channel is hooked up, and we're serializing debug models,
if the result is an already outlined reference, we can emit it directly,
without also outlining the reference. This would create an unnecessary
indirection.
Before:
```
:N1760023808330.2688
0:D"$2"
0:D"$3"
0:D"$4"
0:"hi"
1:{"name":"Component","key":null,"env":"Server","stack":[],"props":{}}
2:{"time":3.0989999999999327}
3:"$1"
4:{"time":3.261792000000014}
```
After:
```
:N1760023786873.8916
0:D"$2"
0:D"$1"
0:D"$3"
0:"hi"
1:{"name":"Component","key":null,"env":"Server","stack":[],"props":{}}
2:{"time":2.4145829999999933}
3:{"time":2.5488749999999527}
```
Notice how the second debug info chunk is now directly referencing chunk
`1` in the debug channel, without outlining and referencing `"$1"` as
its own debug chunk `3`.
This not only simplifies the RSC payload, and reduces overhead. But more
importantly it helps the client resolve cyclic references when a model
has debug info that has a reference back to the model. The client is
currently not able to resolve such a cycle when those chunk indirections
are involved. Ideally, it would also be able to resolve them regardless,
but that requires more work. In the meantime, this fixes an immediate
issue.
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## Summary
<!--
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does the pull request solve?
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Fixes a syntax error causing the Compiler playground to crash. Resolves
https://github.com/facebook/react/issues/34622.
## How did you test this change?
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Tested locally and added a test.
<img width="1470" height="836" alt="Screenshot 2025-09-27 at 8 13 07 AM"
src="https://github.com/user-attachments/assets/29473682-94c3-49dc-9ee9-c2004062aaea"
/>
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Before submitting a pull request, please make sure the following is
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2. Run `yarn` in the repository root.
3. If you've fixed a bug or added code that should be tested, add tests!
4. Ensure the test suite passes (`yarn test`). Tip: `yarn test --watch
TestName` is helpful in development.
5. Run `yarn test --prod` to test in the production environment. It
supports the same options as `yarn test`.
6. If you need a debugger, run `yarn test --debug --watch TestName`,
open `chrome://inspect`, and press "Inspect".
7. Format your code with
[prettier](https://github.com/prettier/prettier) (`yarn prettier`).
8. Make sure your code lints (`yarn lint`). Tip: `yarn linc` to only
check changed files.
9. Run the [Flow](https://flowtype.org/) type checks (`yarn flow`).
10. If you haven't already, complete the CLA.
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## Summary
This pull request fixes a small UI issue in the React Developer Tools
settings panel.
The “Display density” field was appearing twice in the General tab.
Fix : https://github.com/facebook/react/issues/34791
Renames the `recommended` property on LintRule to `preset`, to allow
exporting rules for different presets. For now the `Recommended` and
`RecommendedLatest` presets are the same, but in the next PR I will
enable more rules for the latest preset.
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34782).
* #34783
* __->__ #34782
For 7.0.0:
Slim down presets to just 2 configurations:
- `recommended`: legacy and flat config with all recommended rules, and
- `recommended-latest`: legacy and flat config with all recommended
rules plus new bleeding edge experimental compiler rules
Removed:
- `recommended-latest-legacy`
- `flat/recommended`
Please see the README for new install instructions.
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34757).
* #34783
* #34782
* __->__ #34757
There's a couple of issues with serializing Buffer in the debug renders.
For one, the Node.js Buffer has a `toJSON` on it which turns the binary
data into a JSON array which is very inefficient to serialize compared
to the real buffer. For debug info we never really want to resolve these
and unlike the regular render we can't error. So this uses the trick
where we read the original value. It's still unfortunate that this
intermediate gets created at all but at least now we're not serializing
it.
Second, we have a limit on depth of objects but we didn't have a limit
on width like large arrays or typed arrays. This omits large arrays from
the payload when possible and make them deferred when there's a debug
channel.
## 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.
## Overview
This PR ships the View Transition APIs to `react@canary`:
- [`<ViewTransition
/>`](https://react.dev/reference/react/ViewTransition)
-
[`addTransitionType`](https://react.dev/reference/react/addTransitionType)
This means these APIs are ready for final feedback and prepare for
semver stable release.
## What this means
Shipping `<ViewTransition />` and `addTransitionType` 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
`<ViewTransition />` 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 `<ViewTransition />`.
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
`<ViewTransition>` 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#view-transitions)
blog post, and [the new docs for `<ViewTransition
/>`](https://react.dev/reference/react/ViewTransition) and
[`addTransitionType`](https://react.dev/reference/react/addTransitionType)
for more info.
Adds back HermesParser to eslint-plugin-react-hooks. There are still
[external users of
Flow](https://github.com/facebook/react/pull/34719#issuecomment-3368137743)
using the plugin, so we shouldn't break the plugin for them. However, we
still have the problem of double parsing: once from eslint (which we
discard) and then another via babel/hermes parser.
In the long run we should investigate a translation layer from estree to
babel (or alternatively, update the compiler to take estree as input).
But for now, I am reverting the PR.
This does mean that [Sandpack in
react.dev](https://github.com/reactjs/react.dev/blob/11cb6b591571caf5fa2a192117b6a6445c3f2027/src/components/MDX/Sandpack/runESLint.tsx#L31)
cannot update to the latest eprh as HermesParser does not appear to be
able to be run in a browser. I discovered this while trying to update
eprh on react.dev last week, but didn't investigate deeply. I'll need to
double check that again to find out more.
Another attempt to fix#34745. I updated our fixture for eslint-v9 to
include running tsc. I believe there were 2 issues:
1. `export * from './cjs/eslint-plugin-react-hooks'` in npm/index.d.ts
was no longer correct as we updated index.ts to export default instead
of named exports
2. After fixing ^ there was a typescript error which I fixed by making
some small tweaks
We override Cmd+F to jump to our search input instead of searching
through the HTML. This is ofc critical since our view virtualized.
However, Chrome DevTools installs its own listener on the document as
well (in the bubble phase) so if we prevent it at the document level
it's too late and it ends up stealing the focus instead. If we instead
listen at the documentElement it works as intended.
Joe Savona
Sebastian Markbåge
Joseph Savona
Eugene Choi
Sebastian "Sebbie" Silbermann
Ruslan Lesiutin
Hendrik Liebau
Sophie Alpert
Ian Duvall
Anatole-Godard
lauren