This is intended to be used by various client side resources where the
transfer size is interesting to know how it'll perform in various
network conditions. Not intended to be added by the server.
For now it's only added internally by DevTools itself on img/css but
I'll add it from Flight Client too in a follow up.
This now shows this as the "transfer size" which is the encoded body
size + headers/overhead. Where as the "fileSize" that I add to images is
the decoded body size, like what you'd see on disk. This is what Chrome
shows so it's less confusing if you compare Network tab and this view.
We currently only track the reason something might suspend in
development mode through debug info but this excludes some cases. As a
result we can end up with boundary that suspends but has no cause. This
tries to detect that and show a notice for why that might be. I'm also
trying to make it work with old React versions to cover everything.
In production we don't track any of this meta data like `_debugInfo`,
`_debugThenable` etc. so after resolution there's no information to take
from. Except suspensey images / css which we can track in prod too. We
could track lazy component types already. We'd have to add something
that tracks after the fact if something used a lazy child, child as a
promise, hooks, etc. which doesn't exist today. So that's not backwards
compatible and might add some perf/memory cost. However, another
strategy is also to try to replay the components after the fact which
could be backwards compatible. That's tricky for child position since
there's so many rules for how to do that which would have to be
replicated.
If you're in development you get a different error. Given that we've
added instrumentation very recently. If you're on an older development
version of React, then you get a different error. Unfortunately I think
my feature test is not quite perfect because it's tricky to test for the
instrumentation I just added.
https://github.com/facebook/react/pull/34146 So I think for some
prereleases that has `_debugOwner` but doesn't have that you'll get a
misleading error.
Finally, if you're in a modern development environment, the only reason
we should have any gaps is because of throw-a-Promise. This will
highlight it as missing. We can detect that something threw if a
Suspense boundary commits with a RetryCache but since it's a WeakSet we
can't look into it to see anything about what it might have been. I
don't plan on doing anything to improve this since it would only apply
to new versions of React anyway and it's just inherently flawed. So just
deprecate it #34032.
Note that nothing in here can detect that we suspended Transition. So
throwing at the root or in an update won't show that anywhere.
This computes a min and max range for the whole suspense boundary even
when selecting a single component so that each component in a boundary
has a consistent range.
The start of this range is the earliest start of I/O in that boundary or
the end of the previous suspense boundary, whatever is earlier. If the
end of the previous boundary would make the range large, then we cap it
since it's likely that the other boundary was just an independent
render.
The end of the range is the latest end of I/O in that boundary. If this
is smaller than the end of the previous boundary plus the 300ms
throttle, then we extend the end. This visualizes what throttling could
potentially do if the previous boundary committed right at its end. Ofc,
it might not have committed exactly at that time in this render. So this
is just showing a potential throttle that could happen. To see actual
throttle, you look in the Performance Track.
<img width="661" height="353" alt="Screenshot 2025-08-14 at 12 41 43 AM"
src="https://github.com/user-attachments/assets/b0155e5e-a83f-400c-a6b9-5c38a9d8a34f"
/>
We could come up with some annotation to highlight that this is eligible
to be throttled in this case. If the lines don't extend to the edge,
then it's likely it was throttled.
This shows the stack trace of the JSX at each level so now you can also
jump to the code location for the JSX callsite. The visual is similar to
the owner stacks with `createTask` except when you click the `<...>` you
jump to the Instance in the Components panel.
<img width="593" height="450" alt="Screenshot 2025-08-08 at 12 19 21 AM"
src="https://github.com/user-attachments/assets/dac35faf-9d99-46ce-8b41-7c6fe24625d2"
/>
I'm not sure it's really necessary to have all the JSX stacks of every
owner. We could just have it for the current component and then the rest
of the owners you could get to if you just click that owner instance.
As a bonus, I also use the JSX callsite as the fallback for the "View
Source" button. This is primarily useful for built-ins like `<div>` and
`<Suspense>` that don't have any implementation to jump to anyway. It's
useful to be able to jump to where a boundary was defined.
Stacked on #34101.
This adds a badge to owners if they are different from the currently
selected component's environment.
<img width="590" height="566" alt="Screenshot 2025-08-04 at 5 15 02 PM"
src="https://github.com/user-attachments/assets/e898254f-1b4c-498e-8713-978d90545340"
/>
We also add one to the end of stack traces if the stack trace has a
different environment than the owner which can happen when you call a
function (without rendering a component) into a third party environment
but the owner component was in the first party.
One awkward thing is that Suspense boundaries are always in the client
environment so their Server Components are always badged.
Stacked on #34016.
This is using the same thing we already do for the performance track to
provide a description of the I/O based on the content of the resolved
Promise. E.g. a Response's URL.
<img width="375" height="388" alt="Screenshot 2025-07-28 at 1 09 49 AM"
src="https://github.com/user-attachments/assets/f3fdc40f-4e21-4e83-b49e-21c7ec975137"
/>
This collects the ReactAsyncInfo between instances. It associates it
with the parent. Typically this would be a Server Component's Promise
return value but it can also be Promises in a fragment. It can also be
associated with a client component when you pass a Promise into the
child position e.g. `<div>{promise}</div>` then it's associated with the
div. If an instance is filtered, then it gets associated with the parent
of that's unfiltered.
The stack trace currently isn't source mapped. I'll do that in a follow
up.
We also need to add a "short name" from the Promise for the description
(e.g. url). I'll also add a little marker showing the relative time span
of each entry.
<img width="447" height="591" alt="Screenshot 2025-07-26 at 7 56 00 PM"
src="https://github.com/user-attachments/assets/7c966540-7b1b-4568-8cb9-f25cefd5a918"
/>
<img width="446" height="570" alt="Screenshot 2025-07-26 at 7 55 23 PM"
src="https://github.com/user-attachments/assets/4eac235b-e735-41e8-9c6e-a7633af64e4b"
/>
The `useOpenResource` hook is now used to open links. Currently, the
`<>` icon for the component stacks and the link in the bottom of the
components stack. But it'll also be used for many new links like stacks.
If this new option is configured, and this is a local file then this is
opened directly in the external editor. Otherwise it fallbacks to open
in the Sources tab or whatever the standalone or inline is configured to
use.
<img width="453" height="252" alt="Screenshot 2025-07-24 at 4 09 09 PM"
src="https://github.com/user-attachments/assets/04cae170-dd30-4485-a9ee-e8fe1612978e"
/>
I prominently surface this option in the Source pane to make it
discoverable.
<img width="588" height="144" alt="Screenshot 2025-07-24 at 4 03 48 PM"
src="https://github.com/user-attachments/assets/0f3a7da9-2fae-4b5b-90ec-769c5a9c5361"
/>
When this is configured, the "Open in Editor" is hidden since that's
just the default. I plan on deprecating this button to avoid having the
two buttons going forward.
Notably there's one exception where this doesn't work. When you click an
Action or Event listener it takes you to the Sources tab and you have to
open in editor from there. That's because we use the `inspect()`
mechanism instead of extracting the source location. That's because we
can't do the "throw trick" since these can have side-effects. The Chrome
debugger protocol would solve this but it pops up an annoying dialog. We
could maybe only attach the debugger only for that case. Especially if
the dialog disappears before you focus on the browser again.
In RSC and other stacks now we use a lot of `ReactFunctionLocation` type
to represent the location of a function. I.e. the location of the
beginning of the function (the enclosing line/col) that is represented
by the "Source" of the function. This is also what the parent Component
Stacks represents.
As opposed to `ReactCallSite` which is what normal stack traces and
owner stacks represent. I.e. the line/column number of the callsite into
the next function.
We can start sharing more code by using the `ReactFunctionLocation` type
to represent the component source location and it also helps clarify
which ones are function locations and which ones are callsites as we
start adding more stack traces (e.g. for async debug info and owner
stack traces).
Native only. Displays the native tag for Native Host components inside a
badge, when user inspects the component.
Only displaying will be supported for now, because in order to get
native tags indexable, they should be part of the bridge operations,
which is technically a breaking change that requires significantly more
time investment.
The text will only be shown when user hovers over the badge.
First, this basically reverts
1f3892ef8c
to use a Map/Set to track what is forced to suspend/error again instead
of flags on the Instance. The difference is that now the key in the
Fiber itself instead of the ID. Critically this avoids the
fiberToFiberInstance map to look up whether or not a Fiber should be
forced to suspend when asked by the renderer.
This also allows us to force suspend/error on filtered instances. It's a
bit unclear what should happen when you try to Suspend or Error a child
but its parent boundary is filtered. It was also inconsistent between
Suspense and Error due to how they were implemented.
I think conceptually you're trying to simulate what would happen if that
Component errored or suspended so it would be misleading if we triggered
a different boundary than would happen in real life. So I think we
should trigger the nearest unfiltered Fiber, not the nearest Instance.
The consequence of this however is that if this instance was filtered,
there's no way to undo it without refreshing or removing the filter.
This is an edge case though since it's unusual you'd filter these in the
first place.
It used to be that Suspense walked the store in the frontend and Error
walked the Fibers in the backend. They also did this somewhat eagerly.
This simplifies and unifies the model by passing the id of what you
clicked in the frontend and then we walk the Fiber tree from there in
the backend to lazily find the boundary. However I also eagerly walk the
tree at first to find whether we have any Suspense or Error boundary
parents at all so we can hide the buttons if not.
This also implements it to work with VirtualInstances using #30865. I
find the nearest Fiber Instance downwards filtered or otherwise. Then
from its parent we find the nearest Error or Suspense boundary. That's
because VirtualInstance will always have their inner Fiber as an
Instance but they might not have their parent since it might be
filtered. Which would potentially cause us to skip over a filtered
parent Suspense boundary.
I need to start clarifying where things are really actually Fibers and
where they're not since I'm adding Server Components as a separate type
of component instance which is not backed by a Fiber.
Nothing in the front end should really know anything about what kind of
renderer implementation we're inspecting and indeed it's already not
always a "Fiber" in the legacy renderer.
We typically refer to this as a "Component Instance" but the front end
currently refers to it as an Element as it historically grew from the
browser DevTools Elements tab.
I also moved the renderer.js implementation into the `backend/fiber`
folder. These are at the same level as `backend/legacy`. This clarifies
that anything outside of this folder ideally shouldn't refer to a
"Fiber".
console.js and profilingHooks.js unfortunately use Fibers a lot which
needs further refactoring. The profiler frontend also uses the term
alot.
Stacked on https://github.com/facebook/react/pull/28351, please review
only the last commit.
Top-level description of the approach:
1. Once user selects an element from the tree, frontend asks backend to
return the inspected element, this is where we simulate an error
happening in `render` function of the component and then we parse the
error stack. As an improvement, we should probably migrate from custom
implementation of error stack parser to `error-stack-parser` from npm.
2. When frontend receives the inspected element and this object is being
propagated, we create a Promise for symbolicated source, which is then
passed down to all components, which are using `source`.
3. These components use `use` hook for this promise and are wrapped in
Suspense.
Caching:
1. For browser extension, we cache Promises based on requested resource
+ key + column, also added use of
`chrome.devtools.inspectedWindow.getResource` API.
2. For standalone case (RN), we cache based on requested resource url,
we cache the content of it.
`_debugSource` was removed in
https://github.com/facebook/react/pull/28265.
This PR migrates DevTools to define `source` for Fiber based on
component stacks. This will be done lazily for inspected elements, once
user clicks on the element in the tree.
`DevToolsComponentStackFrame.js` was just copy-pasted from the
implementation in `ReactComponentStackFrame`.
Symbolication part is done in
https://github.com/facebook/react/pull/28471 and stacked on this commit.
Along with all the places using it like the `_debugSource` on Fiber.
This still lets them be passed into `createElement` (and JSX dev
runtime) since those can still be used in existing already compiled code
and we don't want that to start spreading to DOM attributes.
We used to have a DEV mode that compiles the source location of JSX into
the compiled output. This was nice because we could get the actual call
site of the JSX (instead of just somewhere in the component). It had a
bunch of issues though:
- It only works with JSX.
- The way this source location is compiled is different in all the
pipelines along the way. It relies on this transform being first and the
source location we want to extract but it doesn't get preserved along
source maps and don't have a way to be connected to the source hosted by
the source maps. Ideally it should just use the mechanism other source
maps use.
- Since it's expensive it only works in DEV so if it's used for
component stacks it would vary between dev and prod.
- It only captures the callsite of the JSX and not the stack between the
component and that callsite. In the happy case it's in the component but
not always.
Instead, we have another zero-cost trick to extract the call site of
each component lazily only if it's needed. This ensures that component
stacks are the same in DEV and PROD. At the cost of worse line number
information.
The better way to get the JSX call site would be to get it from `new
Error()` or `console.createTask()` inside the JSX runtime which can
capture the whole stack in a consistent way with other source mappings.
We might explore that in the future.
This removes source location info from React DevTools and React Native
Inspector. The "jump to source code" feature or inspection can be made
lazy instead by invoking the lazy component stack frame generation. That
way it can be made to work in prod too. The filtering based on file path
is a bit trickier.
When redesigned this UI should ideally also account for more than one
stack frame.
With this change the DEV only Babel transforms are effectively
deprecated since they're not necessary for anything.
Adds `Forget` badge to all relevant components.
Changes:
- If component is compiled with Forget and using a built-in
`useMemoCache` hook, it will have a `Forget` badge next to its display
name in:
- components tree
- inspected element view
- owners list
- Such badges are indexable, so Forget components can be searched using
search bar.
Fixes:
- Displaying the badges for owners list inside the inspected component
view
Implementation:
- React DevTools backend is responsible for identifying if component is
compiled with Forget, based on `fiber.updateQueue.memoCache`. It will
wrap component's display name with `Forget(...)` prefix before passing
operations to the frontend. On the frontend side, we will parse the
display name and strip Forget prefix, marking the corresponding element
by setting `compiledWithForget` field. Almost the same logic is
currently used for HOC display names.
There are not so many changes, most of them are changing imports,
because I've moved types for UI in a single file.
In https://github.com/facebook/react/pull/27357 I've added support for
pausing polling events: when user inspects an element, we start polling
React DevTools backend for updates in props / state. If user switches
tabs, extension's service worker can be killed by browser and this
polling will start spamming errors.
What I've missed is that we also have a separate call for this API, but
which is executed only once when user selects an element. We don't
handle promise rejection here and this can lead to some errors when user
selects an element and switches tabs right after it.
The only change here is that this API now has
`shouldListenToPauseEvents` param, which is `true` for polling, so we
will pause polling once user switches tabs. It is `false` by default, so
we won't pause initial call by accident.
af8beeebf6/packages/react-devtools-shared/src/backendAPI.js (L96)
Some context:
- When user selects an element in tree inspector, we display current
state of the component. In order to display really current state, we
start polling the backend to get available updates for the element.
Previously:
- Straight-forward sending an event to get element updates each second.
Potential race condition is not handled in any form.
- If user navigates from the page, timeout wouldn't be cleared and we
would potentially throw "Timed out ..." error.
- Bridge disconnection is not handled in any form, if it was shut down,
we could spam with "Timed out ..." errors.
With these changes:
- Requests are now chained, so there can be a single request at a time.
- Handling both navigation and shut down events.
This should reduce the number of "Timed out ..." errors that we see in
our logs for the extension. Other surfaces will also benefit from it,
but not to the full extent, as long as they utilize
"resumeElementPolling" and "pauseElementPolling" events.
Tested this on Chrome, running React DevTools on multiple tabs,
explicitly checked the case when service worker is in idle state and we
return back to the tab.
* 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
Adds the concept of "plugins" to the inspected element payload. Also adds the first plugin, one that resolves StyleX atomic style names to their values and displays them as a unified style object (rather than a nested array of objects and booleans).
Source file names are displayed first, in dim color, followed by an ordered set of resolved style values.
For builds with the new feature flag disabled, there is no observable change.
A next step to build on top of this could be to make the style values editable, but change the logic such that editing one directly added an inline style to the item (rather than modifying the stylex class– which may be shared between multiple other components).
* Restore inspect-element bridge optimizations
When the new Suspense cache was integrated (so that startTransition could be used) I removed a couple of optimizations between the backend and frontend that reduced bridge traffic when e.g. dehydrated paths were inspected for elements that had not rendered since previously inspected. This commit re-adds those optimizations as well as an additional test with a bug fix that I noticed while reading the backend code.
There are two remaining TODO items as of this commit:
- Make inspected element edits and deletes also use transition API
- Don't over-eagerly refresh the cache in our ping-for-updates handler
I will addres both in subsequent commits.
* Poll for update only refreshes cache when there's an update
* Added inline comment
DevTools was built with a fork of an early idea for how Suspense cache might work. This idea is incompatible with newer APIs like `useTransition` which unfortunately prevented me from making certain UX improvements. This PR swaps out the primary usage of this cache (there are a few) in favor of the newer `unstable_getCacheForType` and `unstable_useCacheRefresh` APIs. We can go back and update the others in follow up PRs.
### Messaging changes
I've refactored the way the frontend loads component props/state/etc to hopefully make it better match the Suspense+cache model. Doing this gave up some of the small optimizations I'd added but hopefully the actual performance impact of that is minor and the overall ergonomic improvements of working with the cache API make this worth it.
The backend no longer remembers inspected paths. Instead, the frontend sends them every time and the backend sends a response with those paths. I've also added a new "force" parameter that the frontend can use to tell the backend to send a response even if the component hasn't rendered since the last time it asked. (This is used to get data for newly inspected paths.)
_Initial inspection..._
```
front | | back
| -- "inspect" (id:1, paths:[], force:true) ---------> |
| <------------------------ "inspected" (full-data) -- |
```
_1 second passes with no updates..._
```
| -- "inspect" (id:1, paths:[], force:false) --------> |
| <------------------------ "inspected" (no-change) -- |
```
_User clicks to expand a path, aka hydrate..._
```
| -- "inspect" (id:1, paths:['foo'], force:true) ----> |
| <------------------------ "inspected" (full-data) -- |
```
_1 second passes during which there is an update..._
```
| -- "inspect" (id:1, paths:['foo'], force:false) ---> |
| <----------------- "inspectedElement" (full-data) -- |
```
### Clear errors/warnings transition
Previously this meant there would be a delay after clicking the "clear" button. The UX after this change is much improved.
### Hydrating paths transition
I also added a transition to hydration (expanding "dehyrated" paths).
### Better error boundaries
I also added a lower-level error boundary in case the new suspense operation ever failed. It provides a better "retry" mechanism (select a new element) so DevTools doesn't become entirely useful. Here I'm intentionally causing an error every time I select an element.
### Improved snapshot tests
I also migrated several of the existing snapshot tests to use inline snapshots and added a new serializer for dehydrated props. Inline snapshots are easier to verify and maintain and the new serializer means dehydrated props will be formatted in a way that makes sense rather than being empty (in external snapshots) or super verbose (default inline snapshot format).
