* Add a way to skip/only tests to RulesOfHooks test
* [ESLint] Forbid top-level use*() calls
* Add a regression test for logical expressions
This is not a change. Just adding more coverage.
This patch formalizes the mock native events and event sequences used in unit tests.
The `createEventTarget` function returns an object that can be used to dispatch native event sequences on the target without having to manually do so across all the scenarios we need to account for. Unit tests can be written as if we were only working with PointerEvent, but they will dispatch realistic native event sequences based on the execution environment (e.g., is PointerEvent supported?) and pointer type.
```
describe.each(environments)('Suite', (hasPointerEvents) => {
beforeEach(() => {
// setup
});
test.each(pointerTypes)('Test', (pointerType) => {
const target = createEventTarget(node);
target.pointerdown({pointerType});
expect(callback).toBeCalled();
});
});
```
Every native event that is dispatched now includes a complete object by default. The properties of the events can be customized. Properties that shouldn't be relied on in responder implementations are excluded from the mock native events to ensure tests will fail. Equivalent properties are normalized across different event types, e.g., 'pointerId' is converted to 'identifier' before a TouchEvent is dispatched.
1. Run the tests in both an environment without PointerEvent and one with PointerEvent.
2. Improve test coverage to include both mouse and touch pointers.
3. Change 'Press' so that it only listens to either pointer events or fallbacks events.
* Fixed issue with def being undefined while referencing arguments.
* Removed todo comment.
* Skip exhaustive deps check if def is null.
* Fixed code formatting in ExhaustiveDeps.
* Removed unneeded comment in ExhaustiveDeps.
* [Scheduler] Mark user-timing events
Marks when Scheduler starts and stops running a task. Also marks when
a task is initially scheduled, and when Scheduler is waiting for a
callback, which can't be inferred from a sample-based JavaScript CPU
profile alone.
The plan is to use the user-timing events to build a Scheduler profiler
that shows how the lifetime of tasks interact with each other and
with unscheduled main thread work.
The test suite works by printing an text representation of a
Scheduler flamegraph.
* Expose shared array buffer with profiling info
Array contains
- the priority Scheduler is currently running
- the size of the queue
- the id of the currently running task
* Replace user-timing calls with event log
Events are written to an array buffer using a custom instruction format.
For now, this is only meant to be used during page start up, before the
profiler worker has a chance to start up. Once the worker is ready, call
`stopLoggingProfilerEvents` to return the log up to that point, then
send the array buffer to the worker.
Then switch to the sampling based approach.
* Record the current run ID
Each synchronous block of Scheduler work is given a unique run ID. This
is different than a task ID because a single task will have more than
one run if it yields with a continuation.
Provides partial support for React.lazy() components from the existing PartialRenderer server-side renderer.
Lazy components which are already resolved (or rejected), perhaps with something like `react-ssr-prepass`, can be continued into synchronously. If they have not yet been initialized, they'll be initialized before checking, opening the possibility to exploit this capability with a babel transform. If they're pending (which will typically be the case for a just initialized async ctor) then the existing invariant continues to be thrown.
* Test that we can suspend updates while waiting to hydrate
* Attempt hydration at a higher pri first if props/context changes
* Retrying a dehydrated boundary pings at the earliest forced time
This might quickly become an already expired time.
* Mark the render as delayed if we have to retry
This allows the suspense config to kick in and we can wait for much longer
before we're forced to give up on hydrating.
If we get an insertion after a boundary, that has not yet been hydrated,
we take our best guess at which state the HTML is showing.
isSuspenseInstancePending means that we're still waiting for more server
HTML before we can hydrate. This should mean that we're showing the
fallback state.
isSuspenseInstanceFallback means that we want to client render something.
That most likely means that the server was unable to render and is
displaying a fallback state in this slot.
Adds tests to ensure that dehydrated components don't consider the force
flag.
* Move dehydrated to be child of regular SuspenseComponent
We now store the comment node on SuspenseState instead and that indicates
that this SuspenseComponent is still dehydrated.
We also store a child but that is only used to represent the DOM node for
deletions and getNextHostSibling.
* Move logic from DehydratedSuspenseComponent to SuspenseComponent
Forked based on SuspenseState.dehydrated instead.
* Retry logic for dehydrated boundary
We can now simplify the logic for retrying dehydrated boundaries without
hydrating. This is becomes simply a reconciliation against the dehydrated
fragment which gets deleted, and the new children gets inserted.
* Remove dehydrated from throw
Instead we use the regular Suspense path. To save code, we attach retry
listeners in the commit phase even though technically we don't have to.
* Pop to nearest Suspense
I think this is right...?
* Popping hydration state should skip past the dehydrated instance
* Split mount from update and special case suspended second pass
The DidCapture flag isn't used consistently in the same way. We need
further refactor for this.
* Reorganize update path
If we remove the dehydration status in the first pass and then do a second
pass because we suspended, then we need to continue as if it didn't
previously suspend. Since there is no fragment child etc.
However, we must readd the deletion.
* Schedule context work on the boundary and not the child
* Warn for Suspense hydration in legacy mode
It does a two pass render that client renders the content.
* Rename DehydratedSuspenseComponent -> DehydratedFragment
This now doesn't represent a suspense boundary itself. Its parent does.
This Fiber represents the fragment around the dehydrated content.
* Refactor returns
Avoids the temporary mutable variables. I kept losing track of them.
* Add a comment explaining the type.
Placing it in the type since that's the central point as opposed to spread
out.
This is a bad bug. It means that we sometimes inherit
didReceiveUpdate from a previous component's begin.
Effectively this only means that we're overrendering in some cases.
We should refactor to get rid of this as a global flag.
Separate the PointerEvent and fallback implementations.
Fix the unit tests to cover both PointerEvent and non-PointerEvent environments.
Fix the focus-visible related callbacks to get called when keys other than "Tab" are used.
@acdlite while browsing Twitter, I saw [an opportunity][1] to do
something more productive than browsing Twitter.
[1]: https://twitter.com/acdlite/status/1160247965908234240
Test plan:
`yarn flow-ci`, `yarn test-prod`, `yarn lint`
This code is being compiled incorrectly by something in the Facebook
build pipeline. I'm removing it temporarily to unblock the sync while
we investigate.
Currently this is getting marked as Never which is the normal continuation
for a dehydrated boundary, but if it is client-rendered it has a higher
priority. That causes us to drop the interaction tracing for that render.
This colocates the marking where we actually set the expiration time.
**Problem**
The existing responders listen to pointer events by default and add fallback events if PointerEvent is not supported. However, this complicates the responders and makes it easy to create a problematic unit test environment. jsdom doesn't support PointerEvent, which means that the responders end up listening to pointer events *and* fallback events in unit tests. This isn't a direct problem in production environments, because no browser will fire pointer events if they aren't supported. But in the unit test environment, we often dispatch event sequences taken from browsers that support pointer events. This means that what we're often testing is actually a (complex) scenario that cannot even occur in production: a responder that is listening to and receives both pointer events and fallback events. Not only does this risk making responders more complicated to implement but it could also hide bugs in implementations.
**Response**
Implement the responders so that they're only listening to *either* pointer events *or* fallback events, never both. This should make the default pointer events implementations significantly simpler and easier to test, as well as free to rely on the complete PointerEvents API. In the future it should also make DCE easier for target environments that are known to support PointerEvents, as we can use build tools with an equivalent of the runtime check. The fallback events (touch and mouse) need to coexist and be resilient to browser emulated events. Our unit tests should express a suite of high-level interactions that can be run in environments with and without PointerEvents support.
These were discovered by @SimenB in https://github.com/facebook/react/pull/16332. We weren't making actual assertions on some values. This PR makes the assertions, and fixes the tests.
In a previous version of act(), we used a dummy dom element to flush effects. This doesn't need to exist anymore, and this PR removes it. The warning doesn't need to be there either (React will fire a wrong renderer act warning if needed).
When React detects a deprectated/unsafe lifecycle method, the warning points to a page with more details on the why/what of the warning. However, the actual link (https://fb.me/react-async-component-lifecycle-hooks) uses the phrase "lifecycle-hooks" which is confusing since it doesn't have anything to do with hooks. This PR changes the link to something less confusing - https://fb.me/react-unsafe-component-lifecycles.
Upgraded from Babel 6 to Babel 7.
The only significant change seems to be the way `@babel/plugin-transform-classes` handles classes differently from `babel-plugin-transform-es2015-classes`. In regular mode, the former injects a `_createClass` function that increases the bundle size, and in the latter it removes the safeguard checks. However, this is okay because we don't all classes in new features, and we want to deprecate class usage in the future in the react repo.
Co-authored-by: Luna Ruan <luna@fb.com>
Co-authored-by: Abdul Rauf <abdulraufmujahid@gmail.com>
Co-authored-by: Maksim Markelov <maks-markel@mail.ru>
* [Scheduler] Store Tasks on a Min Binary Heap
Switches Scheduler's priority queue implementation (for both tasks and
timers) to an array-based min binary heap.
This replaces the naive linked-list implementation that was left over
from the queue we once used to schedule React roots. A list was arguably
fine when it was only used for roots, since the total number of roots is
usually small, and is only 1 in the common case of a single-page app.
Since Scheduler is now used for many types of JavaScript tasks (e.g.
including timers), the total number of tasks can be much larger.
Binary heaps are the standard way to implement priority queues.
Insertion is O(1) in the average case (append to the end) and O(log n)
in the worst. Deletion is O(log n). Peek is O(1).
* Sophie nits
We might reenter a hydration state, when attempting to hydrate a boundary.
We need to ensure that we reset it to not hydrating once we exit it.
Otherwise the next sibling will still be in hydration mode.
This happens in this case: `<!--$!--><!--$!-->...<!--/$--><!--/$-->...`
getNextHydratableInstanceAfterSuspenseInstance didn't take
SUSPENSE_FALLBACK_START_DATA or SUSPENSE_PENDING_START_DATA into account
so if a boundary was in one of those states, it wouldn't be considered to
push the stack of boundaries. As a result the first end comment was
considered the end but it really should've been the second end comment.
The next comment then would've been considered something that can be
skipped. However, since the logic in there considered all comments as
"hydratable", it was considered a hydratable node. Since it was considered
a node that didn't actually correspond to anything in the React tree it got
deleted.
The HTML is now `<!--$!--><!--$!-->...<!--/$-->...` and the trailing
content is now hydrated since it did match something.
Next, since this was client rendered, we're going to delete the suspended
boundary by calling clearSuspenseBoundary and then inserting new content.
However, clearSuspenseBoundary *is* aware of SUSPENSE_FALLBACK_START_DATA
and assumes that there must be another `<!--/$-->` after the first one.
As a result it deleted the trailing content from the DOM since it should
be part of the boundary. However, those DOM nodes were already hydrated in
the React tree. So we end up in an inconsistent state.
When we then try to insert the new content we throw as a result.
I think we would have recovered correctly if clearSuspenseBoundary and
getNextHydratableInstanceAfterSuspenseInstance had the *same* bug but
because they were inconsistent we ended up in a bad place.
We have behaviour divergence for act() between prod and dev (specifically, act() + concurrent mode does not flush fallbacks in prod. This doesn't affect anyone in OSS yet)
We also don't have a good story for writing tests in prod (and what from what I gather, nobody really writes tests in prod mode).
We could have wiped out act() in prod builds, except that _we_ ourselves use act() for our tests when we run them in prod mode.
This PR is a compromise to all of this. We will log a warning if you try to use act() in prod mode, and we silence it in our test suites.
When React schedules a rendering task, it passes a `timeout` option
based on its expiration time. This is intended to avoid starvation
by other React updates. However, it also affects the relative priority
of React tasks and other Scheduler tasks at the same level, like
data processing.
This adds a feature flag to disable passing a `timeout` option to
Scheduler. React tasks will always append themselves to the end of
the queue, without jumping ahead of already scheduled tasks.
This does not affect the order in which React updates within a single
root are processed, but it could affect updates across multiple roots.
This also doesn't remove the expiration from Scheduler. It only means
that React tasks are not given special treatment.
Previously, the suspense priority warning was fired even if the Root wasn't suspended. Changed the warning to fire only when the root is suspended.
Also refactored the suspense priority warning so it's easier to read.
The clean-up function of a passive effect (`useEffect`) usually fires
in a post-commit task, after the browser has painted. However, there is
an exception when the component (or its parent) is deleted from the
tree. In that case, we fire the clean-up function during the
synchronous commit phase, the same phase we use for layout effects.
This is a concession to implementation complexity. Calling it in the
passive effect phase would require either traversing the children of the
deleted fiber again, or including unmount effects as part of the fiber
effect list.
Because the functions are called during the sync phase in this case,
the Scheduler priority is Immediate (the one used for layout) instead
of Normal. We may want to reconsider this trade off later.
If there are adjacent updates we bail out of rendering the suspense list
at all but we may still complete the node. We need to reset the render
state in that case.
I restructured so that this is in the same code path so we don't forget it
in the future.
* Add a feature flag to disable legacy context
* Address review
- invariant -> warning
- Make this.context and context argument actually undefined
* Increase test coverage for lifecycles
* Also disable it on the server is flag is on
* Make this.context {} when disabled, but function context is undefined
* Move checks inside
* [act] Wrap IsThisRendererActing in DEV check
So that it doesn't leak into the production bundle. Follow-up to #16240.
* Disable Suspense fallback test in prod
* Bugfix: Priority when effects are flushed early
The priority of passive effects is supposed to be the same as the
priority of the render. This fixes a bug where the priority is sometimes
wrong if the effects are flushed early.
But the priority should really never be higher than Normal Priority.
I'll change that in the next commit.
* Effects never have higher than normal priority
Effects currently have the same priority as the render that spawns them.
This changes the behavior so that effects always have normal priority,
or lower if the render priority is lower (e.g. offscreen prerendering).
The implementation is a bit awkward because of the way `renderRoot`,
`commitRoot`, and `flushPassiveEffects` are split. This is a known
factoring problem that I'm planning to address once 16.9 is released.
In this PR, for tests (specifically, code inside an `act()` scope), we immediately trigger work that would have otherwise required a timeout. This makes it simpler to tests loading/spinner states, and makes tests resilient to changes in React.
For some of our tests(specifically, ReactSuspenseWithNoopRenderer-test.internal), we _don't_ want fallbacks to immediately trigger, because we're testing intermediate states and such. Added a feature flag `flushSuspenseFallbacksInTests` to disable this behaviour on a per case basis.
Concurrent/Batched mode tests should always be run with a mocked scheduler (v17 or not). This PR adds a warning for the same. I'll put up a separate PR to the docs with a page detailing how to mock the scheduler.
Adds experimental flag to yield many times per frame using a message
event loop, instead of the current approach of guessing the next vsync
and yielding at the end of the frame.
This new approach forgoes a `requestAnimationFrame` entirely. It posts a
message event and performs a small amount of work (5ms) before yielding
to the browser, regardless of where it might be in the vsync cycle. At
the end of the event, if there's work left over, it posts another
message event.
This should keep the main thread responsive even for really high frame
rates. It also shouldn't matter if the hardware frame rate changes after
page load (our current heuristic only detects if the frame rate
increases, not decreases).
The main risk is that yielding more often will exacerbate main thread
contention with other browser tasks.
Let's try it and see.
* Do not hyphenate custom CSS property
* Move check into the processStyleName fn
* Formatting
* add test
* Put isCustomProperty check after conditional return
* add test to `ReactDOMServerIntegration` and supress warning
* Don't indexOf twice
* Simpler fix
Not returning the value of flushPassiveEffects() in flushWork() meant that with async act, we wouldn't flush all work with cascading effects. This PR fixes that oversight, and adds some tests to catch this in the future.
The Scheduler implementation uses browser APIs like `MessageChannel`,
`requestAnimationFrame`, and `setTimeout` to schedule work on the main
thread. Most of our tests treat these as implementation details;
however, the sequence and timing of these APIs are not precisely
specified, and can vary wildly across browsers.
To prevent regressions, we need the ability to simulate specific edge
cases that we may encounter in various browsers.
This adds a new test suite that mocks all browser methods used in our
implementation. It assumes as little as possible about the order and
timing of events. The only thing it assumes is that
requestAnimationFrame is passed a frame time that is equal to or less
than the time returned by performance.now. Everything else can be
controlled at will.
It also includes Scheduler-specific invariants, e.g. only one rAF
callback can be scheduled at a time.
It overlaps slightly with the existing SchedulerDOM-test suite, which
also mocks the browser APIs, but exposes a higher-level set of testing
primitives. I will consolidate the two suites in a follow-up.
This adds a 'SuspenseCallback' feature flag. When the property is set on
a suspense component it will be called during the commit phase with a
set of the immediate thenable for this component. This will allow user
code to build runtime tracing of the cause for a suspense boundary.
Given this snippet:
```jsx
TestRenderer.act(() => {
TestUtils.act(() => {
TestRenderer.create(<Effecty />);
});
});
```
We want to make sure that all work is only flushed on exiting the outermost act().
Now, naively doing this based on actingScopeDepth would work with a mocked scheduler, where flushAll() would flush all work across renderers.
This doesn't work without mocking the scheduler though; and where flushing work only works per renderer. So we disable this behaviour for a non-mocked scenario. This seems like an ok tradeoff.
Noticed when looking at the performance profiler with Luna that it's
hard to tell which event causes `performWorkUntilDeadline` to fire
because these functions are anonymous.
Always sets `isRAFLoopRunning` back to false when an animation frame is
scheduled. Fixes a bug where two rAFs fire in the same frame, but the
second one exits and fails to schedule a new rAF.
Fixes bug observed in Safari.
Prevents Spacebar from scrolling the window.
Prevents Enter from triggering a navigation if preventDefault is true.
Fixes the emulated mouse events test.
Improved warning whenever lower priority events (ex. data fetching, page load) happen during a high priority update (ex. hover/click events) to include:
1.) Name of component that triggered the high priority update or
2.) Information that the update was triggered on the root
Scheduler uses `requestAnimationFrame` to post tasks to the browser.
If this happens at the beginning of a frame, the callback might not
fire until the subsequent frame, even if the main thread is idle.
Our theory was that this wouldn't be an issue in practice, because once
the first rAF fires, we schedule the next rAF as early as possible in
that frame. Combined with our heuristic for computing frame deadlines,
we shouldn't get any idle time in between frames — only before the
*first* frame.
This reasoning holds true when you have a small number of large tasks,
such as the ones posted by React. The idle time before the task starts
is negligible relative to the lifetime of the entire task.
However, it does not hold if you have many small tasks posted over a
span of time, perhaps spawned by a flurry of IO events. In this case,
instead of single, contiguous rAF loop preceded by an idle frame, you
get many rAF loops preceded by many idle frames. Our new theory is that
this is contributing to poor main thread utilization during page loads.
To try to reclaim as much idle time as possible, this PR adds two
experimental flags. The first one adds a `requestIdleCallback` call to
start the rAF loop, which will fire before rAF if there's idle time left
in the frame. (We still call rAF in case there isn't. We start working
in whichever event fires first.)
The second flag tries a similar strategy using `setTimeout(fn, 0)`. If
the timer fires before rAF, we'll assume that the main thread is idle.
If either `requestIdleCallback` or `setTimeout` fires before rAF, we'll
immediately peform some work. Since we don't have a real frame time that
we can use to compute the frame deadline, we'll do an entire frame
length of work. This will probably push us past the vsync, but this is
fine because we can catch up during the next frame, by which point a
real rAF will have fired and the loop can proceed the same way it
does today.
Test plan: Try this on Facebook to see if it improves load times
- redoes #15431 from scratch, taking on the feedback there
- unifies the messaging between "deprecated" and UNSAFE_ lifecycle messages. It reorganizes ReactStrictModeWarnings.js to capture and flush all the lifecycle warnings in one procedure each.
- matches the warning from ReactPartialRenderer to match the above change
- passes all the tests
- this also turns on `warnAboutDeprecatedLifecycles` for the test renderer. I think we missed doing so it previously. In a future PR, I'll remove the feature flag altogether.
- this DOES NOT do the same treatment for context warnings, I'll do that in another PR too
This returns the current value of ReactCurrentFiber and enables DevTools to append a custom (owner-only) component stack to warnings and errors in DEV mode.
Real Maps should now be used in RN JS engines. In theory this should
be faster (but might not actually be in practice), and it avoids hitting
upper bounds of property max counts.
We don't use these types of Maps in Fabric.
When executing a task, wraps the callback in an extra function whose
name includes the current priority level. Profiling tools with access
to function names can use this to determine the priority of the task.
1. Allow auxillary button clicks (i.e., middle mouse button) to trigger 'onPressStart' and 'onPressEnd', but never 'onPress'.
2. Report the button type – 'primary' or 'auxillary' – on the press event.
* [fail] reset IsThisRendererActing correctly
I missed this in https://github.com/facebook/react/pull/16039. I'd pointed at the wrong previous state, corrupting it in further use. This PR fixes that, and adds a test to make sure it doesn't happen again.
* warn for unacted effects only in strict mode
* only warn on unacted effects for strict / non sync modes
(basically, when `fiber.mode !== 0b0000`)
Warnings on unacted effects may be too noisy, especially for legacy apps. This PR fires the warning only when in a non sync mode (concurrent/batched), or when in strict mode. This should make updating easier.
I also added batched mode tests to the act() suite.
* explicitly check for modes before warning, explicit tests for all modes
* allow nested `act()`s from different renderers
There are usecases where multiple renderers need to oprate inside an act() scope
- ReactDOM.render being used inside another component tree. The parent component will be rendered using ReactTestRenderer.create for a snapshot test or something.
- a ReactDOM instance interacting with a ReactTestRenderer instance (like for the new devtools)
This PR changes the way the acting sigils operate to allow for this. It keeps 2 booleans, one attached to React, one attached to the renderer. act() changes these values, and the workloop reads them to decide what warning to trigger.
I also renamed shouldWarnUnactedUpdates to warnsIfNotActing
* s/ReactIsActing/IsSomeRendererActing and s/ReactRendererIsActing/IsThisRendererActing
* Add tail="collapsed" option
* Fix issue with tail exceeding the CPU time limit
We used to assume that this didn't suspend but this branch happens in
both cases. This fixes it so that we first check if we suspended.
Now we can fix the tail so that it always render an additional fallback
in this scenario.
* added flush sync test
* added code to run flushSync with ImmediatePriority
* added code to run flushSync with ImmediatePriority
* fixed flow error
* fixed flow error
* Add a bunch of optimizations to SuspenseList
We now are able to bail out of reconciliation and splitting out the tail
during deep updates that hasn't changed the child props. This only
works while the list wasn't suspended before.
I also moved the second render of the "head" to the complete phase. This
cleans it up a bit for the tail collapsing PR.
For this second pass I also use a new technique of resetting the child
Fibers for the second pass. This is effectively a fast path to avoid
reconciling the children against props again.
* Move to didSuspend from SuspenseListState to the effectTag
The effectTag now tracks whether the previous commit was suspended.
This frees up SuspenseListState to be render-phase only state.
We use null to mean the default "independent" mode.
* Rename to SuspenseListState to SuspenseListRenderState
* Reuse SuspenseListRenderState across render passes
* Add optimization to bail out of scanning children if they can't be suspended
This optimized the deep update case or initial render without anything
suspending.
We have some information available to us that tell us if nothing has
suspended in the past and nothing has suspended this render pass.
This also fixes a bug where we didn't tag the previous render as having
suspended boundaries if we didn't need to force a rerender.
* rm printChildren
oops
* Slightly improve performance of hydration.
Avoid loading nodeType and data couple times from the same node in a row,
but instead load them only once, which will help engines to run this code
faster, especially during startup of the application. The general approach
is still not ideal, since hydrating this way forces the browser engine
to materialize JavaScript wrapper objects for all DOM nodes, even if they
are not interesting to hydration itself.
* Fix condition for COMMENT_NODEs.
* Improve general code readability
Preemptively update tests wrt 'parser' requiring an absolute
path rather than a package name, even though the project is
still using ESLint 4.
Fixes#15971
* use toWarnDev for dom fixture tests
forks toWarnDev from root into fixture/dom, updates tes tests to use it
* disable act() warnings for react-art()
- For 'secondary' renderers like react-act, we don't want to fire missing act() warnings; the wrapping renderer will fire warnings anyway, and when it flushes, it flushes effects *across* renderers.
- I could have used isPrimaryRenderer as the flag, but this is marked as false for react-test-renderer, and we *do* want the warning to fire for it. Hence a new flag.
* add missing dependency `art` to fixtures/dom
* Retry failed roots on refresh
* Don't prevent retry after error -> render(null) special case
The check wasn't very resilient because in Concurrent Mode it looks like we can get further follow-up commits even if we captured an error. So we can't reliably distinguish the case where after an error you _manually_ rendered null.
Retrying on an edit after a tree failed _and_ you rendered null in the same tree seems fine. It's also very unlikely a pattern like this actually exists in the wild.
* warn if passive effects get queued outside of an act() call
While the code itself isn't much (it adds the warning to mountEffect() and updateEffect() in ReactFiberHooks), it does change a lot of our tests. We follow a bad-ish pattern here, which is doing asserts inside act() scopes, but it makes sense for *us* because we're testing intermediate states, and we're manually flush/yield what we need in these tests.
This commit has one last failing test. Working on it.
* pass lint
* pass failing test, fixes another
- a test was failing in ReactDOMServerIntegrationHooks while testing an effect; the behaviour of yields was different from browser and server when wrapped with act(). further, because of how we initialized modules, act() around renders wasn't working corrrectly. solved by passing in ReactTestUtils in initModules, and checking on the finally yielded values in the specific test.
- in ReactUpdates, while testing an infinite recursion detection, the test needed to be wrapped in an act(), which would have caused the recusrsion error to throw. solived by rethrowing the error from inside the act().
* pass ReactDOMServerSuspense
* stray todo
* a better message, consistent with the state update one.
* [Scheduler] requestPaint
Signals to Scheduler that the browser needs to paint the screen. React
will call it in the commit phase. Scheduler will yield at the end of
the current frame, even if there is no pending input.
When `isInputPending` is not available, this has no effect, because we
yield at the end of every frame regardless.
React will call `requestPaint` in the commit phase as long as there's at
least one effect. We could choose not to call it if none of the effects
are DOM mutations, but this is so rare that it doesn't seem worthwhile
to bother checking.
* Fall back gracefully if requestPaint is missing
At the end of each frame, Scheduler yields control of the main thread so
the browser can execute important tasks; most importantly, painting the
screen and responding to user input. There's some overhead involved in
regaining control of the main thread, so we'd like to yield as
infrequently as possible to keep the UI responsive.
The reason we yield on every frame is because there's no way for us to
know whether we're blocking user input.
`isInputPending` is an experimental browser API that gives us this
information. It tells us whether there's a pending user input, which
also means it tells us if there's *not* a pending user input. We can use
this signal to decide whether it's OK not to yield.
There's a max frame length after which we'll yield regardless, as a
precaution against blocking non-input tasks that we don't know about.
* Expire rendering the tail of SuspenseList after a timeout
This is the first Suspense feature that isn't actually dependent on IO.
The thinking here is that it's normal for a SuspenseList to show loading
states, and it'll be designed to handle it one at a time.
However, sometimes there are lists with really big items that take a long
time to CPU render. Since data can become available as we do that, it is
likely that we have all the data and become CPU bound.
In that case, the list would naively just render until the end and then
display all items at once. I think that's actually what you want for fast
lists. However, for slow ones (like News Feed), you're better off showing
a few rows at a time.
It's not necessarily one at a time because if you can do many in a short
period of time and fit them all on the screen, then it's better to do them
all at once than pop them in one at a time very quickly.
Therefore, I use a heuristic of trying to render as many rows as I can in
500ms before giving up.
This timer starts before the first row of the tail and we only check it
after. This ensures that we always make a little progress each attempt.
An alternative approach could be to start the time before doing the head
of the list but we don't want that being slow prevent us from making
further progress.
Currently, I disable this optimization at Never priority because there's
nothing intermediate that becomes visible anyway.
* Fix tracing through a SuspenseList
This ensures that we can spawn new work during render through arbitrary
priorities.
We'll need this for other features too.
Since each priority can commit separately we need to use an array to
include the current interactions on each priority.
The responder region calculation logic wasn't updating the deactivation region
during the lifetime of an event instance, causing incorrect behaviour when the
current press ends outside the press target and if the press target has moved
since the last time the first-and-only time the deactivation region was
measured.
* Add forwards option
* Add backwards option
* Add comment
* Add customized warning messages for case and typos
* Add some more tests for insertions and updates in start/middle/end
* reset scope depth on synchronous errors
we weren't resetting the acting scope depth on sync errors thrown in the callback. this fixes that.
* typos
* add a test to make sure sync error propagate
* Add SuspenseList component type
* Push SuspenseContext for SuspenseList
* Force Suspense boundaries into their fallback state
In the "together" mode, we do a second render pass that forces the
fallbacks to stay in place, if not all can unsuspend at once.
* Add test
* Transfer thennables to the SuspenseList
This way, we end up retrying the SuspenseList in case the nested boundary
that just suspended doesn't actually get mounted with this set of
thennables. This happens when the second pass renders the fallback
directly without first attempting to render the content.
* Add warning for unsupported displayOrder
* Add tests for nested sibling boundaries and nested lists
* Fix nested SuspenseList forwarding thennables
* Rename displayOrder to revealOrder
Display order has some "display list" connotations making it sound like
a z-index thing.
Reveal indicates that this isn't really about when something gets rendered
or is ready to be rendered. It's about when content that is already there
gets to be revealed.
* Add test for avoided boundaries
* Make SuspenseList a noop in legacy mode
* Use an explicit suspense list state object
This will be used for more things in the directional case.
* Track mounted roots via DevTools Hook
* Add helper utilities to the runtime
These utilities will likely be needed by all module systems, so let's just put them here.
* Wrap more things in __DEV__
* Fix tests to also be DEV-only
Adds a `delay` option to `scheduleCallback`. When specified, the task is
not scheduled until after the delay has elapsed.
Delayed tasks are scheduled on a timer queue maintained by Scheduler,
instead of directly with the browser. The main benefit is to reduce the
number of native browser timers that Scheduler's `message` event handler
has to contend with; so, after yielding to the browser at the end of the
frame, Scheduler will more quickly regain control of the main thread.
Because we're able to flush the timer queue without yielding to browser
timer events, there's also less task switching overhead (though in the
absence of `isInputPending`, this is mostly a theoretical win since we
yield every frame regardless).
If the queue of non-delayed tasks is non-empty — that is, if there is
pending CPU bound work — Scheduler is able to avoid a browser timer
entirely by periodically checking its own timer queue while flushing
tasks (inside the `message` event handler). Once the CPU-bound work is
complete, if there are still pending delayed tasks, Scheduler will
schedule a single browser timer that fires once the earliest delay
has elapsed.
* [scheduler] Internal rename: Callback -> Task
Rename Callback type to Task. Does not affect the public API, only
internal names, though eventually we'll probably want to align with the
WICG Main-thread Scheduling proposal
(https://github.com/WICG/main-thread-scheduling).
* [scheduler] flushFirstTask() -> flushTask(task)
Pass task as an argument to `flushTask` instead of using a module-
level variable.
* [scheduler] Add startTime field
This does not change any semantics, but in the future `startTime` may
represent a future time, to support delayed tasks.
* [Scheduler] Use continuation pattern for host cb
As I prepare to implement integrated timers, I noticed some
peculiarities in the Scheduler implementation that could afford to be
cleaned up.
This is a refactor and shouldn't affect any observable behavior; mostly
it removes some concepts that existed in earlier iterations of Scheduler
and are no longer needed.
The main change is to how the DOM implementation schedules an additional
callback before yielding to the main thread. It used to follow the same
code path for scheduling task; now it has its own branch directly
inside the message event handler. The special case for error handling
— where we call `postMessage` immediately without waiting for rAF —
has similarly been localized inside the catch block of the message
event handler.
* Rename `disableContextMenu` to `preventContextMenu`
* Change the behaviour of `preventContextMenu` so that `onContextMenu` is still called when the native context menu is prevented.
* Run Fresh tests in two modes: with and without destructuring
Destructuring transform messes up the way we collect signatures for Hooks. This adds failing tests.
* Extract collecting calls to Hooks into a separate visitor
This introduces a bit of a perf penalty but makes our plugin resilient to presence of destructuring transform and their order. Fixes new tests.
* Inline some logic into the call visitor
Follow up to #15861.
Turns out you can't set `!important` using a normal property assignment.
You have to use `style.setProperty`.
Maybe Andrew *should* just learn CSS.
IE9 doesn't support `style.setProperty` so we'll fall back to setting
`display: none` without `important`, like we did before #15861 Our
advice for apps that need to support IE9 will be to avoid using
`!important`. Which seems like good advice in general, but IANACSSE.
Tested on FB and using our Suspense DOM fixture.
Suspended nodes are hidden using an inline `display: none` style. We do
this instead of removing the nodes from the DOM so that their state is
preserved when they are shown again.
Inline styles have the greatest specificity, but they are superseded by
`!important`. To prevent an external style from overriding React's, this
commit changes the hidden style to `display: none !important`.
MaYBE AnDREw sHOulD JusT LEArn Css
I attempted to write a unit test using `getComputedStyle` but JSDOM
doesn't respect `!important`. I think our existing tests are sufficient
but if we were to decide we need something more robust, I would set up
an e2e test.
* Fix existing test
This test included a change in variable name. It wasn't needed, and distracts from the actual thing being tested (the annotation).
* Reset state on edits to initial state argument
* Add a way to check whether there are hot updates
prepareUpdate() now returns null if there are none.
* Add a way to query host nodes for families
* Split the signature call into two calls
This adds a render-time signature call by making __signature__ curried. We need both calls. The init time tells us which type has which signature. The render time call says when's a good time to capture the lazy Hooks tree. This is necessary for supporting inline requires. I will do that in next commit.
* Lazily compute Hook list on first render
This ensures inline requires don't break comparisons between Hook signatures of previous and next versions by caching Hook list at the time of first render.
* Refactor computing Hook signature keys
Instead of a traversal during the comparison, explicitly compute full keys. This makes it easier to debug mismatches.
* Remount classes during hot reload
* Fix a crash when Hook isn't in scope inside the signature
* Minor tweaks
* Support a comment annotation to force state reset
* Refactoring: pass a function instead of WeakMap
This hides the implementation a little bit and reduces how much React knows about the underlying mechanism.
* Refactor: use forceReset to remount unknown Hooks
We already have the logic to reset a component, so let's just reuse it instead of that special case.
* Same as previous commit, but for Flare
I don't know what the public API for setting the event priority should
be. Right now it accepts a numeric enum, but is this what we want?
Maybe it should be a string enum? I've punted on this for now.
* Add test for hover events
* [Events] Add EventPriority enum
React DOM's DispatchConfig for synthetic events has an `isDiscrete`
field that affects how updates triggered by an event are scheduled.
Events are either discrete or continuous.
This commit adds an additional type of configuration where an event
has user-blocking priority, but is not discrete. E.g. updates triggered
by hover are more important than the default, but they don't need to
be processed serially. Because there are now three types of event
priority instead of two, I've replaced the `isDiscrete` boolean with an
enum: `eventPriority`.
This commit implements the new enum value but does not change any
behavior. I'll enable it behind a feature flag in the next commit.
I've only implemented this in the legacy event system. I'll leave Flare
for a follow-up.
* enableUserBlockingEvents feature flag
Adds a feature flag to increase the priority of events like `mouseover`,
without making them discrete.
Compare the viewport-relative coordinates of getBoundingClientRect with those
of the event's client{X,Y} values. This fixes press within scrollable nodes.
This commit is a follow-up to https://github.com/facebook/react/pull/15604, which explains more of the rationale behind moving React Native to path-based imports and the work needed in the React repository. In that linked PR, the generated renderers were updated but not the shims; this commit updates the shims.
The problem is that FB needs a different copy of the built renderers than the OSS versions so we need a way for FB code to import different modules than in OSS. This was previously done with Haste, but with the removal of Haste from RN, we need another mechanism. Talking with cpojer, we are using a `.fb.js` extension that Metro can be configured to prioritize over `.js`.
This commit generates FB's renderers with the `.fb.js` extension and OSS renderers with just `.js`. This way, FB can internally configure Metro to use the `.fb.js` implementations and OSS will use the `.js` ones, letting us swap out which implementation gets bundled.
Test Plan: Generated the renderers and shims with `yarn build` and then verified that the generated shims don't contain any Haste-style imports. Copied the renderers and shims into RN manually and launched the RNTester app to verify it loads end-to-end. Added `.fb.js` to the extensions in `metro.config.js` and verified that the FB-specific bundles loaded.
If an event in the old system is dispatched synchronously within an
event from the new system, or vice versa, and the inner event is a
discrete update, React should not flush pending discrete updates before
firing the inner event's handlers, even if the outer event is not
discrete.
Another way of saying this is that nested events should never force
React to flush discrete updates.
Arguably, if the outer event is not a discrete event, then the inner
event _should_ flush the pending events. However, that would be a
breaking change. I would argue this isn't so bad, however, given that
nested events are pretty rare. They don't fit nicely into our event
model regardless, since we don't support nested React renders. In the
future we should consider warning when events are nested.
WorkPhase is an enum that represents the currently executing phase of
the React update -> render -> commit cycle. However, in practice, it's
hard to use because different "phases" can be nested inside each other.
For example, the commit phase can be nested inside the
"batched phase."
This replaces WorkPhase with a different concept: ExecutionContext.
ExecutionContext is a bitmask instead of an enum. It represents a stack
of React entry points. For example, when `batchedUpdates` is called
from inside an effect, the ExecutionContext is
`BatchedContext | CommitContext`.
* Fix issue with Tab+alt not being considered as isGlobalFocusVisible candidate on Mac
* Add test for Tab+alt on Mac setting pointerType: "keyboard" on a focus event
* Track most recent commit time of a fallback globally
This value is going to be used to avoid committing too many fallback
states in quick succession. It doesn't really matter where in the tree
that happened.
This means that we now don't really need the concept of SuspenseState
other than has a flag. It could be made cheaper/simpler.
* Change suspense heuristic
This now eagerly commits non-delayed suspended trees, unless they're
only retries in which case they're throttled to 500ms.
* Restart early if we're going to suspend later
* Use the local variable where appropriate
* Make ReactLazy tests less specific on asserting intermediate states
They're not testing the exact states of the suspense boundaries, only
the result. I keep assertions that they're not already resolved early.
* Adjust Profiler tests to the new heuristics
* Update snapshot tests for user timing tests
I also added a blank initial render to ensuree that we cover the suspended
case.
* Adjust Suspense tests to account for new heuristics
Mostly this just means render the Suspense boundary first so that it
becomes an update instead of initial mount.
* Track whether we have a ping on the currently rendering level
If we get a ping on this level but have not yet suspended, we might
still suspend later. In that case we should still restart.
* Add comment about moving markers
We should add this to throwException so we get these markers earlier.
I've had to rewrite tests that test restarting to account for the delayed
restarting heuristic.
Ideally, we should also be able to restart from within throwException if
we're already ready to restart. Right now we wait until the next yield.
* Add test for restarting during throttled retry
* Add test that we don't restart for initial render
* Add Suspense Heuristics as a comment in Throw
The previous naming scheme used the name of the resulting bundle file.
However, there are cases where multiple bundles have the same filename.
This meant whichever bundle finishes last overwrites the previous ones
with the same name.
The updated naming scheme is `bundle-sizes-<CI_NODE_INDEX>.json`.
Instead of generating a separate info file per bundle, it now creates
one per process.
* warn when using the wrong renderer's act around another renderer's updates
like it says. it uses a real object as the sigil (instead of just a boolean). specifically, it uses a renderer's flushPassiveEffects as the sigil. We also run tests for this separate from our main suite (which doesn't allow loading multiple renderers in a suite), but makes sure to run this in CI as well.
* unneeded (and wrong) comment
* run the dom fixture on CI
* update the sigil only in __DEV__
* remove the obnoxious comment
* use an explicit export for the sigil
* Write size info to separate file per bundle
`bundle-sizes.json` contains the combined size information for every
build. This makes it easier to store and process, but it prevents us
from parallelizing the build script, because each process would need to
write to the same file.
So I've updated the Rollup script to output individual files per build.
A downstream CI job consolidates them into a single file.
I have not parallelized the Rollup script yet. I'll do that next.
* Parallelize the build script
Uses CircleCI's `parallelism` config option to spin up multiple build
processes.
Removes `--extract-errors` argument from CI build script command.
Instead, the author is expected to run `yarn extract-errors` locally
or manually edit the error code map.
The lint rule should be sufficient to catch unminified errors, but
as an extra precaution, I added a post-build step that greps the
production bundles. The post-build step works even if someone disables
the lint rule for a specific line or file.
* Lint rule for unminified errors
Add a lint rule that fails if an invariant message is not part of the
error code map.
The goal is to be more disciplined about adding and modifiying
production error codes. Error codes should be consistent across releases
even if their wording changes, for continuity in logs.
Currently, error codes are added to the error code map via an automated
script that runs right before release. The problem with this approach is
that if someone modifies an error message in the source, but neglects to
modify the corresponding message in the error code map, then the message
will be assigned a new error code, instead of reusing the existing one.
Because the error extraction script only runs before a release, people
rarely modify the error code map in practice. By moving the extraction
step to the PR stage, it forces the author to consider whether the
message should be assigned a new error code. It also allows the reviewer
to review the changes.
The trade off is that it requires more effort and context to land new
error messages, or to modify existing ones, particular for new
contributors who are not familiar with our processes.
Since we already expect users to lint their code, I would argue the
additional burden is marginal. Even if they forget to run the lint
command locally, they will get quick feedback from the CI lint job,
which typically finishes within 2-3 minutes.
* Add unreleased error messages to map
* Generate signatures for Hooks
This currently only works one level deep. For custom Hooks, we'll need to add some way to compose signatures.
* Be more resilient to plugin conflicts
This prevents a class of problems where other plugins cause our visitor to re-run.
It's a standard Babel practice, e.g.:
8c7d4b55c9/packages/babel-plugin-transform-react-constant-elements/src/index.js (L85-L86)
* Remove unnecessary stuff from debugging
* Include Foo.useHookName() calls into the signature
* Add an integration test for adding/removing an effect
* Add integration test for changing custom Hook order
* Include custom Hooks into the signatures
* Fix inferred names for function expressions
* Support export default hoc(Foo) when Foo is defined separately
* Add more built-in Hooks
expirationTime has already been checked if it's sync.
timeout can now be longer than 5 seconds when a suspense config is used.
We might want to adjust the heuristics but it's not internally consistent
without this.
Sometimes the status of the `build` job is not in the first page of
the `/statuses` endpoint. The combined `/status` endpoint consolidates
the entries, though, so it always appears there.
* Refactor component search to prepare for deeper traversals
* Register HOCs with intermediate results
* Register components that are used as JSX types
* Add integration test skeleton
The integration test combines testing runtime together with the Babel plugin. It's a bit harder to debug because multiple things can go wrong, but it helps us build confidence that specific scenarios work well.
* Add HOC integration test and fix conflict with JSX transform
* Infer usage from createElement too
This helps us avoid dependency on the plugin order.
* Remove outdated comments
* Wrap tests in __DEV__
* Support export default hoc(...) for anonymous functions
* Fix test indentation
* Fix comment typo
* Use named function for test as this case is more important
* Rename ReactFiberScheduler to ReactFiberWorkLoop
The scheduling part is mostly extracted out to the scheduler package.
What's remaining is mostly around the loop around each section of work.
I name it something with Work in it because it's very related to the
BeginWork, CompleteWork and UnwindWork sections.
* Extract throwException from UnwindWork
Our throwing works more like algebraic effects in that it's a separate
phase where we find a handler and we later unwind.
* [react-native] Use path-based imports instead of Haste for the RN renderer
To move React Native to standard path-based imports instead of Haste, the RN renderer that is generated from the code in this repo needs to use path-based imports as well since the generated code is vendored by RN. This commit makes it so the interface between the generated renderers and RN does not rely on Haste and instead uses a private interface explicitly defined by RN. This inverts control of the abstraction so that RN decides the internals to export rather than React deciding what to import.
On RN's side, a new module named `react-native/Libraries/ReactPrivate/ReactNativePrivateInterface` explicitly exports the modules used by the renderers in this repo. (There is also a private module for InitializeCore so that we can import it just for the side effects.) On React's side, the various renderer modules access RN internals through the explicit private interface.
The Rollup configuration becomes slimmer since the only external package is now `react-native`, and the individual modules are instead listed out in `ReactNativePrivateInterface`.
Task description: https://github.com/facebook/react-native/issues/24770
Sister RN PR (needs to land before this one): https://github.com/facebook/react-native/pull/24782
Test Plan: Ran unit tests and Flow in this repo. Generated the renderers and manually copied them over to the RN repo. Ran the RN tests and launched the RNTester app.
* Access natively defined "nativeFabricUIManager" instead of importing it
Some places in the Fabric renderers access `nativeFabricUIManager` (a natively defined global) instead of importing UIManager. While this is coupling across repos that depends on the timing of events, it is necessary until we have a way to defer top-level imports to run after `nativeFabricUIManager` is defined. So for consistency we use `nativeFabricUIManager` everywhere (see the comment in https://github.com/facebook/react/pull/15604#pullrequestreview-236842223 for more context).
The sizebot scrapes the GitHub `/statuses` endpoint to get the lastest
CircleCI build number for master, in order to fetch the bundle size
info for that build, which are stored as build artifacts. (There's gotta
be a better way to do this, but that's what we have for now.) This
updates the script to match the name of the updated CircleCI job that
generates the bundle sizes.
* Add initial Babel plugin implementation
* Register exported functions
* Fix missing declarations
Always declare them at the bottom and rely on hoisting.
* Remove unused code
* Don't pass filename to tests
I've decided for now that the plugin doesn't need filename, and it will be handled by module runtime integration instead.
* Fix bugs
* Coalesce variable declarations
Updates the CircleCI config to use the workflows features to run jobs in
parallel, instead of the `parallelism` option. This change alone doesn't
improve the overall build time much, since almost all of the total time
is spent running the Rollup script, which runs entirely sequentially.
But it does improve reporting, and should make it easier to add
additional parallel jobs in the future.
* Fix missing return pointer assignment
I found a bug using the fuzz tester that manifested as incorrect
ordering of children in the host tree, but whose root cause was a
missing `return` pointer assignment on a work-in-progress fiber.
Usually return pointers are set during reconciliation
(`reconcileChildFibers`) but this particular assignment happens inside
the custom reconciliation implementation used by Suspense boundaries.
I would not be surprised if there were similar bugs related to incorrect
return pointers. You're supposed to update the return pointer
whenever a work-in-progress fiber is created, but there's nothing in
the contract of the `createFiber` or `createWorkInProgress` function
that implies this. I propose that we update their signatures to accept
the return fiber as an argument. I will do this in a follow-up.
In this commit, I rearranged `updateSuspenseComponent` slightly so that
every call to `createWorkInProgress` or a `createFiber*` function is
immediately followed by a return pointer assignment.
I hardcoded the fuzz test case that surfaced the bug.
* Update all progressed children in list
`progressedPrimaryChild` is a list, not a single fiber. Need to iterate
through every child and update their return pointers.
* Add a stub for React Fresh Babel plugin package
* Move ReactFresh-test into ReactFresh top level directory
* Add a stub for React Fresh Runtime entry point
* Extract Fresh runtime from tests into its entry point
* Don't traverse children when hot reloading needs a remount
If we're gonna remount that tree anyway, there is no use in traversing its children beforehand.
* Add a test verifying hot reload batches updates
Otherwise there is a risk of it being super slow due to cascades.
* Add a minimal failing test for hot reload
* Set up scaffolding for React Fresh
* Consider type family when comparing elementType
Rendering an element with stale type should not cause it to remount.
We only do this for FunctionComponent tag since checking is unnecessary for classes or host components.
* Add support for forwardRef()
Initially I thought I would compare families of inner .render functions.
However, there is a corner case where this can create false positives. Such as when you forwardRef(X) the same X twice. Those are supposed to be distinct. But if we compare .render functions, we wouldn't be able to distinguish them after first reload.
It seems safer to rely on explicit registration for those. This should be easy when forwardRef() call is in the same file, and usually it would be. For cases like HOCs and style.div`...` factories that return forwardRef(), we could have the __register__ helper itself "dig deeper" and register the inner function.
* Show how forwardRef inner identity can be inferred
The __register__ implementation can read the inner identity itself.
* Add missing __DEV__ to tests
* Add support for memo() (without fixing bailouts)
This adds rudimentary support for memo components. However, we don't actually skip bailouts yet, so this is not very useful by itself alone. Tests have TODOs that we need to remove after bailout skipping is done.
* Refactor type comparison for clarity
* Hot update shouldn't re-render ancestor components unnecessarily
My code had a bug where it checked for a wrong thing in a wrong set, leading us to always re-render.
This fixes the checks so that we only schedule updates for things that were actually edited.
* Add test coverage for memo(fn, areEqual)
* Explicitly skip bailouts for hot reloading fibers
This forces even memo() with shallow comparison to re-render on hot update.
* Refactor scheduling update to reduce duplication
* Remove unused variable in test
* Don't check presence in a set while not hot reloading
* Make scheduleHotUpdate() take named arguments
* Don't keep unedited component types in the type => family map
It's unnecessary because if they haven't been edited, there's no special reconciliation logic.
* Add signatures that force remounting
Signatures let us force a remount of a type even if from React's point of view, type is the same.
A type has one current signature. If that signature changes during next hot update, all Fibers with that type should be deleted and remounted.
We do this by mutating elementType scheduling a parent.
This will be handy to force remount of mismatching Hooks, as well as failed error boundaries.
For this to fully work, we'll need to add a way to skip built-in bailouts for all Fiber types. This will be the most invasive and annoying change. I did it for HostRoot in this PR but there's more. I'll add an automated test case that catches the missing bailout bailouts.
* Support forced remounting for all component types
This teaches all parent component types to remount their child if necessary.
It also adds tests for them.
* Remount effects while preserving state for hot reloaded components
This makes sure that changes to *code* always propagate.
It can break components that aren't resilient to useEffect over-firing, but that seems like a good constraint since you might need to add a dependency later anyway, and this helps avoid coding yourself into the corner.
* Add missing __DEV__ blocks to tests
* Fix unused variables in tests
* Remove outdated TODO
* Expose scheduleHotUpdate directly
* Inline isCompatibleType
* Run one check per component for invalidating deps
This also makes the bailouts more targeted--no need to remount useEffect for a parent component of remounted fiber.
* Resolve .type early
This moves resolving to set up the right .type early instead of doing this before render.
A bit more future-proof in case we want to restructure the begin phase later.
ForwardRef is special because its type is a wrapper but it can be hot reloaded by itself.
So we have a special overload for it that reconstucts the wrapper type if needed.
* Add a Suspense todo
* Use current.type !== workInProgress.type for ignoring deps
This gets rid of one of the sets.
* Use workInProgress.type !== current.type check for force re-render
We still use a set for forced remount though.
* Use wip.type !== current.type check in more places
This also disables the remounting tests. They need a separate approach.
* Use a dedicated remount mechanism
* Add a test for offscreen trees
It has a TODO because it seems like offscreen updates are incorrectly applied too soon.
* Enable offscreen test now that it is fixed
* Fix corner cases in the new remounting mechanism
* Remount failed error boundaries on hot reload
* Fix test now that act() flushes
This test is manual so I don't actually want act here.
* Nits
* Add comments
* Add suspendIfNeeded API and a global scope to track it
Adds a "current" suspense config that gets applied to all updates scheduled
during the current scope.
I suspect we might want to add other types of configurations to the "batch"
so I called it the "batch config".
This works across renderers/roots but they won't actually necessarily go
into the same batch.
* Add the suspenseConfig to all updates created during this scope
* Compute expiration time based on the timeout of the suspense config
* Track if there was a processed suspenseConfig this render pass
We'll use this info to suspend a commit for longer when necessary.
* Mark suspended states that should be avoided as a separate flag
This lets us track which renders we want to suspend for a short time vs
a longer time if possible.
* Suspend until the full expiration time if something asked to suspend
* Reenable an old test that we can now repro again
* Suspend the commit even if it is complete if there is a minimum delay
This can be used to implement spinners that don't flicker if the data
and rendering is really fast.
* Default timeoutMs to low pri expiration if not provided
This is a required argument in the type signature but people may not
supply it and this is a user facing object.
* Rename to withSuspenseConfig and drop the default config
This allow opting out of suspending in some nested scope.
A lot of time when you use this function you'll use it with high level
helpers. Those helpers often want to accept some additional configuration
for suspense and if it should suspend at all. The easiest way is to just
have the api accept null or a suspense config and pass it through. However,
then you have to remember that calling suspendIfNeeded has a default.
It gets simpler by just saying tat you can pass the config. You can have
your own default in user space.
* Track the largest suspense config expiration separately
This ensures that if we've scheduled lower pri work that doesn't have a
suspenseConfig, we don't consider its expiration as the timeout.
* Add basic tests for functionality using each update mechanism
* Fix issue when newly created avoided boundary doesn't suspend with delay
* Add test for loading indicator with minLoadingDurationMs option
* s/flushPassiveEffects/unstable_flushWithoutYielding
a first crack at flushing the scheduler manually from inside act(). uses unstable_flushWithoutYielding(). The tests that changed, mostly replaced toFlushAndYield(...) with toHaveYielded(). For some tests that tested the state of the tree before flushing effects (but still after updates), I replaced act() with bacthedUpdates().
* ugh lint
* pass build, flushPassiveEffects returns nothing now
* pass test-fire
* flush all work (not just effects), add a compatibility mode
of note, unstable_flushWithoutYielding now returns a boolean much like flushPassiveEffects
* umd build for scheduler/unstable_mock, pass the fixture with it
* add a comment to Shcduler.umd.js for why we're exporting unstable_flushWithoutYielding
* run testsutilsact tests in both sync/concurrent modes
* augh lint
* use a feature flag for the missing mock scheduler warning
I also tried writing a test for it, but couldn't get the scheduler to unmock. included the failing test.
* Update ReactTestUtilsAct-test.js
- pass the mock scheduler warning test,
- rewrite some tests to use Scheduler.yieldValue
- structure concurrent/legacy suites neatly
* pass failing tests in batchedmode-test
* fix pretty/lint/import errors
* pass test-build
* nit: pull .create(null) out of the act() call
Uses a dynamic flag in www's test renderer build so we can condtionally
disable the passive effects bugfix. Matches the dynamic flag used in
the www React DOM build.
PR #15650 is a bugfix but it's technically a semantic change that could
cause regressions. I don't think it will be an issue, since the
previous behavior was both broken and incoherent, but out of an
abundance of caution, let's wrap it in a flag so we can easily revert
it if necessary.
* Failing test for false positive warning
* Flush passive effects before discrete events
Currently, we check for pending passive effects inside the `setState`
method before we add additional updates to the queue, in case those
pending effects also add things to the queue.
However, the `setState` method is too late, because the event that
caused the update might not have ever fired had the passive effects
flushed before we got there.
This is the same as the discrete/serial events problem. When a serial
update comes in, and there's already a pending serial update, we have to
do it before we call the user-provided event handlers. Because the event
handlers themselves might change as a result of the pending update.
This commit moves the `flushPassiveEffects` call to before the discrete
event handlers are called, and removes it from the `setState` method.
Non-discrete events will not cause passive effects to flush, which is
fine, since by definition they are not order dependent.
If React finishes rendering a tree, delays committing it (e.g.
Suspense), then subsequently starts over or renders a new tree, the
pending tree is no longer valid. That's because rendering a new work-in
progress mutates the old one in place.
The current structure of the work loop makes this hard to reason about
because, although `renderRoot` and `commitRoot` are separate functions,
they can't be interleaved. If they are interleaved by accident, it
either results in inconsistent render output or invariant violations
that are hard to debug.
This commit adds an invariant that throws if the new tree is the same as
the old one. This won't prevent all bugs of this class, but it should
catch the most common kind.
To implement the invariant, I store the finished tree on a field on the
root. We already had a field for this, but it was only being used for
the unstable `createBatch` feature.
A more rigorous way to address this type of problem could be to unify
`renderRoot` and `commitRoot` into a single function, so that it's
harder to accidentally interleave the two phases. I plan to do something
like this in a follow-up.
* Add ReactDOM.unstable_createSyncRoot
- `ReactDOM.unstable_createRoot` creates a Concurrent Mode root.
- `ReactDOM.unstable_createSyncRoot` creates a Batched Mode root. It
does not support `createBatch`.
- `ReactDOM.render` creates a Legacy Mode root. It will eventually be
deprecated and possibly moved to a separate entry point, like
`react-dom/legacy`.
* Rename internal ReactRoot types
* Add Batched Mode
React has an unfortunate quirk where updates are sometimes synchronous
-- where React starts rendering immediately within the call stack of
`setState` — and sometimes batched, where updates are flushed at the
end of the current event. Any update that originates within the call
stack of the React event system is batched. This encompasses most
updates, since most updates originate from an event handler like
`onClick` or `onChange`. It also includes updates triggered by lifecycle
methods or effects. But there are also updates that originate outside
React's event system, like timer events, network events, and microtasks
(promise resolution handlers). These are not batched, which results in
both worse performance (multiple render passes instead of single one)
and confusing semantics.
Ideally all updates would be batched by default. Unfortunately, it's
easy for components to accidentally rely on this behavior, so changing
it could break existing apps in subtle ways.
One way to move to a batched-by-default model is to opt into Concurrent
Mode (still experimental). But Concurrent Mode introduces additional
semantic changes that apps may not be ready to adopt.
This commit introduces an additional mode called Batched Mode. Batched
Mode enables a batched-by-default model that defers all updates to the
next React event. Once it begins rendering, React will not yield to
the browser until the entire render is finished.
Batched Mode is superset of Strict Mode. It fires all the same warnings.
It also drops the forked Suspense behavior used by Legacy Mode, in favor
of the proper semantics used by Concurrent Mode.
I have not added any public APIs that expose the new mode yet. I'll do
that in subsequent commits.
* Suspense in Batched Mode
Should have same semantics as Concurrent Mode.
* Use RootTag field to configure type of root
There are three types of roots: Legacy, Batched, and Concurrent.
* flushSync should not flush batched work
Treat Sync and Batched expiration times separately. Only Sync updates
are pushed to our internal queue of synchronous callbacks.
Renamed `flushImmediateQueue` to `flushSyncCallbackQueue` for clarity.
* Don't consider "Never" expiration as part of most recent event time
This doesn't happen with deprioritization since those are not "updates"
by themselves so they don't go into this accounting.
However, they are real updates if they were scheduled as Idle pri using
the scheduler explicitly. It's unclear what suspense should do for these
updates. For offscreen work, we probably want them to commit immediately.
No point in delay them since they're offscreen anyway. However if this is
an explicit but very low priority update that might not make sense.
So maybe this means that these should have different expiration times?
In this PR I just set the suspense to the lowest JND.
However, we don't want is for these things to commit earlier in case
they got batched in with other work so I also ensured that they're not
accounted for in in the workInProgressRootMostRecentEventTime calculation
at all. This makes them commit immediately if they're by themselves, or
after the JND of whatever they were batched in with.
Ultimately, I think that we should probably never schedule anything at
Never that isn't truly offscreen so this should never happen.
However, that begs the question what happens with very low pri work that
suspends. Do we always work at that level first?
* Adjust test to account for the new shorter suspense time
* Warn when suspending at wrong priority
Adds a warning when a user-blocking update is suspended.
Ideally, all we would need to do is check the current priority level.
But we currently have no rigorous way to distinguish work that was
scheduled at user- blocking priority from work that expired a bit and
was "upgraded" to a higher priority. That's because we don't schedule
separate callbacks for every level, only the highest priority level per
root. The priority of subsequent levels is inferred from the expiration
time, but this is an imprecise heuristic.
However, we do store the last discrete pending update per root. So we
can reliably compare to that one. (If we broaden this warning to include
high pri updates that aren't discrete, then this won't be sufficient.)
My rationale is that it's better for this warning to have false
negatives than false positives.
Potential follow-ups:
- Bikeshed more on the message. I don't like what I landed on that much
but I think it's good enough to start.
- Include the names of the components that updated. (The ideal place to
fire the warning is during the setState call but we don't know if
something will suspend until the next update. Maybe we could be clever
and warn during a subsequent update to the same component?)
* Move Suspense priority check to throwException
* Fixes a bug in the cancellation logic. The cancel events are now correctly listened to on the root.
* Fixes cancellation in Safari by using the dragstart event as a proxy for cancellation (i.e., the event dispatched when move-during-press occurs on an anchor tag)
* [React Native] Inline calls to FabricUIManager in shared code
* Call global.nativeFabricUIManager directly as short term fix
* Add flow types
* Add nativeFabricUIManager global to eslint config
* Adding eslint global to bundle validation script
Called when focus visibility changes. Focus is only considered visible if a
focus event occurs after keyboard navigation. This provides a way for people to
provide visual focus styles for keyboard accessible UIs without those styles
appearing if focus is triggered by mouse, touch, pen.
This patch fixes an issue related to determining whether the end event occurs
within the responder region. Previously we only checked if the event target was
within the responder region for moves, otherwise we checked if the target was
within the event component. Since the dimensions of the child element can
change after activation, we need to recalculate the responder region before
deactivation as well if the target is not within the event component.
* ADD: disablePictureInPicture attribute for HTML5 videos
* ADD: disablePictureInPicture as DOMProperty and attribute
* Update: Replace camelCase with lowercase and vice-versa
* FIX: Missing comma on attribute (prettier)
https://webpack.js.org/plugins/define-plugin/
Webpack's DefinePlugin has the ability to replace `typeof expr` to a constant in compile-time, which should lead to better dead-code-elimination.
Bugfix for `inferPriorityFromExpirationTime` function. It happened to
work in our existing tests because we use virtual time.
Flow would have caught this if expiration times were an opaque type. We
should consider that in the future. (The downside of opaque types is
that all operations would have to go through helper functions, which may
or may not get inlined by Closure.)
Fixes a bug where the timeout passed to `scheduleCallback` represented
an absolute timestamp, instead of the amount of time until that
timestamp is reached. The solution is to subtract the current time
from the expiration.
The bug wasn't caught by other tests because we use virtual times that
default to 0, and most tests don't advance time.
I also moved the `initialTimeMs` offset to the
`SchedulerWithReactIntegration` module so that we don't have to remember
to subtract the offset every time. (We should consider upstreaming this
to the Scheduler package.)
The implementation is wrong, but also it's not that useful for
debugging. Implementing it properly would involve tracking more
information than we do currently. Perhaps including the priority
of the callback in the message would be helpful, but not sure. For now
I'll just remove it.
Refactor of Press and additional regression coverage.
The logic for "start", "move", "end", and "cancel" events is consolidated into a single block to reduce duplication and improve consistency of the UX across input-types. Also reduces code size.
The bailout logic for anchor tags is removed since we preventDefault for click by default. We can discuss scenarios where it makes sense to limit functionality around interactions on anchor tags.
The logic for ignoring emulated events is simplified and improved. Pointer events can produce emulated touch (immediately after pointer) and mouse events (delayed) which is now accounted for and tested.
This patch makes a change to the Focus module so that it only reports
focus/blur on the host node that's a direct child of the event component. This
brings the expected behaviour in line with the browser default of focus/blur
events not bubbling for Pressable.
Moves the cancelTimeout call to right before creating a new work-in-
progress root. Fixes a class of bugs where a pending commit is not
cancelled, causing an incomplete tree to accidentally commit.
In the interest of fixing downstream bugs quickly, I'm landing this
without a test case; I'll add one in a follow up.
The Pointer Events spec mentions that the value of `button` in a nativeEvent
can be anything between 0 and 5 for "down" events. We only care about those
with a value of 0.
1. Fix hiding context menu for longpress via touch.
2. Fix scrolling of viewport for longpress via spacebar key.
3. Add tests for anchor-related behaviour and preventDefault.
4. Add a deactivation delay for forced activation
5. Add pointerType to Press events.
NOTE: this currently extends pointerType to include `keyboard`.
NOTE: React Native doesn't have a deactivation delay for forced activation, but this is possibly because of the async bridge meaning that the events aren't dispatched sync.
This implementation differs from equivalents in React Native in the following ways:
1. A move during a press will not cancel onLongPress.
2. A move to outside the retention target will cancel the press and not
reactivate when moved back within the retention target.
* Track the earliest event time in this render
Rebase
* Track the time of the fallback being shown as an event time
When we switch back from fallback to content, we made progress and we track
the time from when we showed the fallback in the first place as the
last time we made progress.
* Don't retry if synchronous
* Only suspend when we switch to fallback mode
This ensures that we don't resuspend unnecessarily if we're just retrying
the same exact boundary again. We can still unnecessarily suspend
for nested boundaries.
* Rename timedOutAt to fallbackExpirationTime
* Account for suspense in devtools suspense test
The React Native build does not minify error messages in production,
but it still needs to run the error messages transform to compile
`invariant` calls to `ReactError`. To do this, I added a `noMinify`
option to the Babel plugin. I also renamed it from
`minify-error-messages` to the more generic `transform-error-messages`.
* [React Native] Add tests to paper renderer for measure, measureLayout
* [React Native] measure calls will now call FabricUIManager
The Fabric renderer was previously calling the paper UIManager's measure calls and passing the react tag. This PR changes the renderer to now call FabricUIManager passing the node instead.
One of the parts of this that feels more controversial is making NativeMethodsMixin and ReactNative.NativeComponent warn when calling measureLayout in Fabric. As Seb and I decided in https://github.com/facebook/react/pull/15126, it doesn't make sense for a component created with one of these methods to require a native ref but not work the other way around. For example: a.measureLayout(b) might work but b.measureLayout(a) wouldn't. We figure we should keep these consistent and continue migrating things off of NativeMethodsMixin and NativeComponent.
If this becomes problematic for the Fabric rollout then we should revisit this.
* Fixing Flow
* Add FabricUIManager to externals for paper renderer
* import * as FabricUIManager from 'FabricUIManager';
* Update tests
* Shouldn't have removed UIManager import
* Update with the new tests
We use bitwise operations to compute expiration times, which means they
need to be smaller than 31 bits. So we measure times relative to module
initialization, similar to `performance.now`.
This was already working in the old fiber scheduler, but we didn't have
a test for it.
When an async update expires, React renders at the expiration time that
corresponds to the current time, not at the original update's expiration
time. That way, all the expired work in the tree is flushed in a
single batch.
This is implemented inside `renderRoot` by comparing the next render
expiration time to the current time. If the current time is later,
`renderRoot` will restart at the later time.
Because of poor factoring, the check is currently performed right before
entering the work loop. But the work loop is usually entered multiple
times in a single callback: each time a component throws or suspends.
This led to an infinite loop where React would detect that an update
expired, restart at the current time, make a bit of progress, suspend,
check for expired work again, and start the loop again.
I fixed this by moving the expired work check to the beginning of
`renderRoot`, so that it is not performed every time something suspends.
This isn't ideal, because you could technically still fall into a loop
if more than 10ms lapse in between exiting `renderRoot` and entering it
again. The proper fix is to lift the check outside of `renderRoot`
entirely so that the function can restart without checking for expired
work again. Since this is exceedingly unlikely (and this whole thing is
still behind a flag), I'll do the better fix in an already-planned
follow up to fork `renderRoot` into separate functions for sync and
async work.
* Add HoverProps type
* Add more Hover event module tests
* Add more Press event module tests
* Change default longPress delay from 1000 to 500
* Rename dispatchPressEvent -> dispatchEvent
* Consolidate state updates in Press event module
* Add keyboard support for Press events
* Add FocusProps type and unit tests
* Allow DevTools to toggle Suspense state
* Change API to overrideSuspense
This lets detect support for overriding Suspense from DevTools.
* Add ConcurrentMode test
* Newlines
* Remove unnecessary change
* Naming changes
* Store FB bundles as CI artifacts
Updates the Circle CI config to store Facebook bundles as build
artifacts. We already do this for our npm packages.
* Might as well store everything in build/
* Store build directory as a tarball
So it's easy to download
This doesn't rely on checking the tag. When the alternate of a parent
is missing, it assumes it's a fragment indirection and moves onto the
next parent fiber.
The Facebook build of React DOM uses a forked entry point that exposes
additional secret internals. I didn't account for this when I added
the react-dom/unstable-new-scheduler build, so the extra internals
are currently missing. This commit adds them.
Verified that a variant of this test fails as follows when the
`context.withAsyncDispatching` function is excluded (i.e., reproduces the
issue).
Expected value to equal:
["press", "longpress", "longpresschange"]
Received:
["press", "longpress", "longpress", "longpresschange"]
* Rewrite ReactFiberScheduler
Adds a new implementation of ReactFiberScheduler behind a feature flag.
We will maintain both implementations in parallel until the new one
is proven stable enough to replace the old one.
The main difference between the implementations is that the new one is
integrated with the Scheduler package's priority levels.
* Conditionally add fields to FiberRoot
Some fields only used by the old scheduler, and some by the new.
* Add separate build that enables new scheduler
* Re-enable skipped test
If synchronous updates are scheduled by a passive effect, that work
should be flushed synchronously, even if flushPassiveEffects is
called inside batchedUpdates.
* Passive effects have same priority as render
* Revert ability to cancel the current callback
React doesn't need this anyway because it never schedules callbacks if
it's already rendering.
* Revert change to FiberDebugPerf
Turns out this isn't neccessary.
* Fix ReactFiberScheduler dead code elimination
Should initialize to nothing, then assign the exports conditionally,
instead of initializing to the old exports and then reassigning to the
new ones.
* Don't yield before commit during sync error retry
* Call Scheduler.flushAll unconditionally in tests
Instead of wrapping in enableNewScheduler flag.
This took a while, but I'm happy I went through it. Some key moments - recursively flushing effects, flushing microtasks on each async turn, and my team's uncompromising philosophy on code reuse. Really happy with this. I still want to expand test coverage, and I have some more small related todos, but this is good to land. On to the next one.
Soundtrack to landing this - https://open.spotify.com/track/0MF8I8OUo8kytiOo8aSHYq?si=gSWqUheKQbiQDXzptCXHTg
* hacked up act(async () => {...})
* move stuff around
* merge changes
* abstract .act warnings and stuff. all renderers. pass all tests.
* move testutils.act back into testutils
* move into scheduler, rename some bits
* smaller bundle
* a comment for why we don't do typeof === 'function'
* fix test
* pass tests - fire, prod
* lose actContainerElement
* tighter
* write a test for TestRenderer
it's an odd one, because not only does sync act not flush effects correctly, but the async one does (wut). verified it's fine with the dom version.
* lint
* rewrote to move flushing logic closer to the renderer
the scheduler's `flushPassiveEffects` didn't work as expected for the test renderer, so I decided to go back to the hack (rendering a dumb container) This also makes reactdom not as heavy (by a few bytes, but still).
* move it around so the delta isn't too bad
* cleanups
fix promise chaining
propagate errors correctly
test for thenable the 'right' way
more tests!
tidier!
ponies!
* Stray comment
* recursively flush effects
* fixed tests
* lint, move noop.act into react-reconciler
* microtasks when checking if called, s/called/calledLog, cleanup
* pass fb lint
we could have globally changed our eslint config to assume Promise is available, but that means we expect a promise polyfill on the page, and we don't yet. this code is triggered only in jest anyway, and we're fairly certain Promise will be available there. hence, the once-off disable for the check
* shorter timers, fix a test, test for Promise
* use global.Promise for existence check
* flush microtasks
* a version that works in browsers (that support postMessage)
I also added a sanity fixture inside fixtures/dom/ mostly for me.
* hoist flushEffectsAndMicroTasks
* pull out tick logic from ReactFiberScheduler
* fix await act (...sync) hanging
- fix a hang when awaiting sync logic
- a better async/await test for test renderer
* feedback changes
- use node's setImmediate if available
- a warning if MessageChannel isn't available
- rename some functions
* pass lint/flow checks (without requiring a Promise polyfill/exclusion)
* prettier
the prettiest, even.
* use globalPromise for the missed await warning
* __DEV__ check for didWarnAboutMessageChannel
* thenables and callbacks instead of promises, pass flow/lint
* tinier. better.
- pulled most bits out of FiberScheduler
- actedUpdates uses callbacks now
* pass build validation
* augh prettier
* golfing 7 more chars
* Test that effects are not flushed without also flushing microtasks
* export doesHavePendingPassiveEffects, nits
* createAct()
* dead code
* missed in merge?
* lose the preflushing bits
* ugh prettier
* removed `actedUpdates()`, created shared/actingUpdatesScopeDepth
* rearrange imports so builds work, remove the hack versions of flushPassiveEffects
* represent actingUpdatesScopeDepth as a tuple [number]
* use a shared flag on React.__SECRET...
* remove createAct, setup act for all relevant renderers
* review feedback
shared/enqueueTask
import ReactSharedInternals from 'shared/ReactSharedInternals';
simpler act() internals
ReactSharedInternals.ReactShouldWarnActingUpdates
* move act() implementation into createReactNoop
* warnIfNotCurrentlyActingUpdatesInDev condition check order
* Add Press responder event tests
Behavior being tested takes cues from React Native's Pressability.
A couple of these tests fail and require the Press implementation to be patched.
* Add PressProps type to event module
* Move default Press event delays to constants
* Fix right-click press check for Safari
* Prettier and Linter
* Use event.key in press responder
event.keyCode is a deprecated API
* Remove unused props from Press event module
Note: this is for an experimental event API that we're testing out internally at Facebook.
* onPressIn -> onPressStart
* onPressOut -> onPressEnd
* longPressCancelsPress -> onLongPressShouldCancelPress
* ReactNative's ref.measureLayout now takes a ref
* Use Object as the additional param type
* Remove unnecessary whitespace
* Not supporting ref in mixin or subclass
Make sure that `onPressChange` is only called if `longPressCancelsPress` is `false`.
And make sure that `onLongPressChange` is called when a long press ends.
The 'longpress' event is dispatched during a press interaction, rather than
after it has ended.
The 'longPressCancelsPress' prop can be used to prevent 'press' being
dispatched if 'longpress' has already been dispatched.
I inline it into performAsyncWork instead.
Code that was only relevant to the async callback had leaked into the
performWork call which is an indication that this was a bad abstraction
and therefore the wrong place to DRY.
By inlining I also discovered that minExpirationTime is actually irrelevant
in the yieldy case so we can clean that up.
* Isolate ReactUpdates-test cases
This ensures their behavior is consistent when run in isolation, and that they actually test the cases they're describing.
* Add coverage for cases where we reset nestedUpdateCounter
These cases explicitly verify that we reset the counter in right places.
* Add a mutually recursive test case
* Add test coverage for useLayoutEffect loop
Adds a feature flag `enableNewScheduler` that toggles between two
implementations of ReactFiberScheduler. This will let us land changes in
master while preserving the ability to quickly rollback.
Ideally this will be a short-lived fork. Once we've tested the new
scheduler for a week or so without issues, we will get rid of it. Until
then, we'll need to maintain two parallel implementations and run tests
against both of them. We rarely land changes to ReactFiberScheduler, so
I don't expect this will be a huge burden.
This commit does not implement anything new. The flag is still off and
tests run against the existing implementation.
Use `yarn test-new-scheduler` to run tests against the new one.
MDN has a list of methods for obtaining the window reference of an
iframe:
https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage#Syntax
fix(react-dom): check if iframe belongs to the same origin
Accessing the contentDocument of a HTMLIframeElement can cause the browser
to throw, e.g. if it has a cross-origin src attribute.
Safari will show an error in the console when the access results in "Blocked a frame with origin". e.g:
```javascript
try {
$0.contentDocument.defaultView
} catch (err) {
console.log('err', err)
}
> Blocked a frame with origin X from accessing a frame with origin Y. Protocols, domains, and ports must match.
> err – TypeError: null is not an object (evaluating '$0.contentDocument.defaultView')
```
A safety way is to access one of the cross origin properties: Window or Location
Which might result in "SecurityError" DOM Exception and it is compatible to Safari.
```javascript
try {
$0.contentWindow.location.href
} catch (err) {
console.log('err', err)
}
> err – SecurityError: Blocked a frame with origin "http://localhost:3001" from accessing a cross-origin frame. Protocols, domains, and ports must match.
```
https://html.spec.whatwg.org/multipage/browsers.html#integration-with-idl
* Transform invariant to custom error type
This transforms calls to the invariant module:
```js
invariant(condition, 'A %s message that contains %s', adj, noun);
```
Into throw statements:
```js
if (!condition) {
if (__DEV__) {
throw ReactError(`A ${adj} message that contains ${noun}`);
} else {
throw ReactErrorProd(ERR_CODE, adj, noun);
}
}
```
The only thing ReactError does is return an error whose name is set
to "Invariant Violation" to match the existing behavior.
ReactErrorProd is a special version used in production that throws
a minified error code, with a link to see to expanded form. This
replaces the reactProdInvariant module.
As a next step, I would like to replace our use of the invariant module
for user facing errors by transforming normal Error constructors to
ReactError and ReactErrorProd. (We can continue using invariant for
internal React errors that are meant to be unreachable, which was the
original purpose of invariant.)
* Use numbers instead of strings for error codes
* Use arguments instead of an array
I wasn't sure about this part so I asked Sebastian, and his rationale
was that using arguments will make ReactErrorProd slightly slower, but
using an array will likely make all the functions that throw slightly
slower to compile, so it's hard to say which way is better. But since
ReactErrorProd is in an error path, and fewer bytes is generally better,
no array is good.
* Casing nit
* Add more info to invalid hook call error message
* Update other renderers + change call to action
* Update related tests for new hooks error message
* Fix lint errors
* Eager bailout optimization should always compare to latest reducer
* queue.eagerReducer -> queue.lastRenderedReducer
This name is a bit more descriptive.
* Add test case that uses preceding render phase update
* Throw away old shallow renderer state on type change
This worked in function components but was broken for classes. It incorrectly retained the old instance even if the type was different.
* Remove _previousComponentIdentity
We only needed this because we didn't correctly reset based on type. Now we do so this can go away.
* Use _reset when unmounting
* Use arbitrary componentIdentity
There was no particular reason it was set to element.type. We just wanted to check if something is a render phase update.
* Support Hook state updates in shallow renderer
* Support React.memo in ReactShallowRenderer
ReactShallowRenderer uses element.type frequently, but with React.memo
elements the actual type is element.type.type. This updates
ReactShallowRenderer so it uses the correct element type for Memo
components and also validates the inner props for the wrapped
components.
* Allow Rect.memo to prevent re-renders
* Support memo(forwardRef())
* Dont call memo comparison function on initial render
* Fix test
* Small tweaks
* Set 'size' attribute to select tag if it occurs before appending options
* Add comment about why size is assigned on select create. Tests
I added some more clarification for why size must be set on select
element creation:
- In the source code
- In the DOM test fixture
- In a unit test
* Use let, not const in select tag stub assignment
* Hydration Fixture: Only load ReactDOMServer if it exists
Fixes an issue where the hydration fixture would try to load in
ReactDOMServer below version 14. In version 13, string markup methods
exist on the React namespace.
* DOM Fixtures: Use class component for App.js
This was breaking React 0.13.0.
* Hydration Fixture: better findDOMNode compatibility
This commit fixes an issue where the Hydration DOM fixture was
unusable in React 0.13.0 or lower because of newer API usage.
It fixes that by avoiding the use of refs to get the textarea
reference in the code editor component, using various versions of
findDOMNode as required.
* Hydration Fixture: Do not show dropdown for single-line errors
If an error showed for the hydration fixture, a detail element was
used even if no additional lines could display. In that case, this
commit changes the component such that it returns a div.
* Deeper React version support for hydration fixture
This commit adds support for versions 0.4.0 of React and higher for
the hydration fixture.
The DOM test fixtures themselves do not support down to React 0.4.0,
which would be exhaustive. Instead, the Hydration fixture can pick a
version to use for its own purposes. By default, this is the version
of React used by the fixtures.
In the process of doing this, I had to make some updates to the
renderer.html document associated with the hydration fixture, and I've
added some comments to better document the history of API changes.
* Prevent javascript protocol URLs
* Just warn when disableJavaScriptURLs is false
This avoids a breaking change.
* Allow framesets
* Allow <html> to be used in integration tests
Full document renders requires server rendering so the client path
just uses the hydration path in this case to simplify writing these tests.
* Detect leading and intermediate characters and test mixed case
These are considered valid javascript urls by browser so they must be
included in the filter.
This is an exact match according to the spec but maybe we should include
a super set to be safer?
* Test updates to ensure we have coverage there too
* Fix toString invocation and Flow types
Right now we invoke toString twice when we hydrate (three times
with the flag off). Ideally we should only do it once even in this case
but the code structure doesn't really allow for that right now.
* s/itRejects/itRejectsRendering
* Dedupe warning and add the unsafe URL to the warning message
* Add test that fails if g is added to the sanitizer
This only affects the prod version since the warning is deduped anyway.
* Fix prod test
* Split props changing from permanent fallback state
These will need different logic. In this commit, no logic has changed,
only moved.
* Delete terminal fallback content in first pass
If the dehydrated suspense boundary's fallback content is terminal there
is nothing to show. We need to get actual content on the screen soon.
If we deprioritize that work to offscreen, then the timeout heuristics will
be wrong.
Therefore, if we have no current and we're already at terminal fallback
state we'll immediately schedule a deletion and upgrade to real suspense.
* Show failing case when there is another wrapper boundary
* Revert "Delete terminal fallback content in first pass"
This reverts commit ad67ba8928c23f5d9ba22d7e5c202bf27d0e49d3.
* Use the new approach of leaving work at normal pri to replace fallback
* Add command to run tests in persistent mode
* Convert Suspense fuzz tester to use noop renderer
So we can run it in persistent mode, too.
* Don't mutate stateNode in appendAllChildren
We can't mutate the stateNode in appendAllChildren because the children
could be current.
This is a bit weird because now the child that we append is different
from the one on the fiber stateNode. I think this makes conceptual
sense, but I suspect this likely breaks an assumption in Fabric.
With this approach, we no longer need to clone to unhide the children,
so I removed those host config methods.
Fixes bug surfaced by fuzz tester. (The test case that failed was the
one that's already hard coded.)
* In persistent mode, disable test that reads a ref
Refs behave differently in persistent mode. I added a TODO to write
a persistent mode version of this test.
* Run persistent mode tests in CI
* test-persistent should skip files without noop
If a file doesn't reference react-noop-renderer, we shouldn't bother
running it in persistent mode, since the results will be identical to
the normal test run.
* Remove module constructor from placeholder tests
We don't need this now that we have the ability to run any test file in
either mutation or persistent mode.
* Revert "test-persistent should skip files without noop"
Seb objected to adding shelljs as a dep and I'm too lazy to worry about
Windows support so whatever I'll just revert this.
* Delete duplicate file
* Convert ReactSuspensePlaceholder tests to use noop
Instead of the test renderer, since test renderer does not support
running in persistent mode.
* Run Placeholder tests in persistent mode, too
* Fix Flow and lint
* Hidden text instances should have correct host context
Adds a test for a subtle edge case that only occurs in persistent mode.
* createHiddenTextInstance -> cloneHiddenTextInstance
This sidesteps the problem where createHiddenTextInstance needs access
to the host context.
* A clearer message for props destructuring where applicable
* Add line number to the "move function" message
* Add a hint for how to fix callbacks from props
* Simplify code and harden tests
* Collect all dependency references for better warnings
* Suggest updater or reducer where appropriate
* Import Scheduler directly, not via host config
We currently schedule asynchronous tasks via the host config. (The host
config is a static/build-time dependency injection system that varies
across different renderers — DOM, native, test, and so on.) Instead of
calling platform APIs like `requestIdleCallback` directly, each renderer
implements a method called `scheduleDeferredCallback`.
We've since discovered that when scheduling tasks, it's crucial that
React work is placed in the same queue as other, non-React work on the
main thread. Otherwise, you easily end up in a starvation scenario where
rendering is constantly interrupted by less important tasks. You need a
centralized coordinator that is used both by React and by other
frameworks and application code. This coordinator must also have a
consistent API across all the different host environments, for
convention's sake and so product code is portable — e.g. so the same
component can work in both React Native and React Native Web.
This turned into the Scheduler package. We will have different builds of
Scheduler for each of our target platforms. With this approach, we treat
Scheduler like a built-in platform primitive that exists wherever React
is supported.
Now that we have this consistent interface, the indirection of the host
config no longer makes sense for the purpose of scheduling tasks. In
fact, we explicitly do not want renderers to scheduled task via any
system except the Scheduler package.
So, this PR removes `scheduleDeferredCallback` and its associated
methods from the host config in favor of directly importing Scheduler.
* Missed an extraneous export
* Warn on mount when deps are not an array
* Check other Hooks
* I can't figure out how to fix error/warning nesting lint
But it doesn't really matter much because we test other cases in the other test.
* Revert #14756 changes to ReactFiberScheduler
This PR introduced some bugs in concurrent mode during internal testing.
Until we figure out a proper solution, I'm going to try reverting it.
Not totally certain this is sufficient to unbreak the bugs we found, but
I'm using this branch to determine that.
* Add back commented out Scheduler import
With a note not to use named imports next time we import Scheduler
in this module.
* ReactDebugHooks identifies State and Reducer hooks as editable
* Inject overrideHookState() method to DevTools to support editing in DEV builds
* Added an integration test for React DevTools, react-debug-tools, and overrideHookState
* Swap expect(ReactNoop) for expect(Scheduler)
In the previous commits, I upgraded our custom Jest matchers for the
noop and test renderers to use Scheduler under the hood.
Now that all these matchers are using Scheduler, we can drop
support for passing ReactNoop and test roots and always pass
Scheduler directly.
* Externalize Scheduler in noop and test bundles
I also noticed we don't need to regenerator runtime in noop anymore.
* Replace test renderer's fake Scheduler implementation with mock build
The test renderer has its own mock implementation of the Scheduler
interface, with the ability to partially render work in tests. Now that
this functionality has been lifted into a proper mock Scheduler build,
we can use that instead.
* Fix Profiler tests in prod
* Replace noop's fake Scheduler implementation with mock Scheduler build
The noop renderer has its own mock implementation of the Scheduler
interface, with the ability to partially render work in tests. Now that
this functionality has been lifted into a proper mock Scheduler build,
we can use that instead.
Most of the existing noop tests were unaffected, but I did have to make
some changes. The biggest one involved passive effects: previously, they
were scheduled on a separate queue from the queue that handles
rendering. After this change, both rendering and effects are scheduled
in the Scheduler queue. I think this is a better approach because tests
no longer have to worry about the difference; if you call `flushAll`,
all the work is flushed, both rendering and effects. But for those few
tests that do care to flush the rendering without the effects, that's
still possible using the `yieldValue` API.
Follow-up: Do the same for test renderer.
* Fix import to scheduler/unstable_mock
* Add new mock build of Scheduler with flush, yield API
Test environments need a way to take control of the Scheduler queue and
incrementally flush work. Our current tests accomplish this either using
dynamic injection, or by using Jest's fake timers feature. Both of these
options are fragile and rely too much on implementation details.
In this new approach, we have a separate build of Scheduler that is
specifically designed for test environments. We mock the default
implementation like we would any other module; in our case, via Jest.
This special build has methods like `flushAll` and `yieldValue` that
control when work is flushed. These methods are based on equivalent
methods we've been using to write incremental React tests. Eventually
we may want to migrate the React tests to interact with the mock
Scheduler directly, instead of going through the host config like we
currently do.
For now, I'm using our custom static injection infrastructure to create
the two builds of Scheduler — a default build for DOM (which falls back
to a naive timer based implementation), and the new mock build. I did it
this way because it allows me to share most of the implementation, which
isn't specific to a host environment — e.g. everything related to the
priority queue. It may be better to duplicate the shared code instead,
especially considering that future environments (like React Native) may
have entirely forked implementations. I'd prefer to wait until the
implementation stabilizes before worrying about that, but I'm open to
changing this now if we decide it's important enough.
* Mock Scheduler in bundle tests, too
* Remove special case by making regex more restrictive
* Refactor hook ordering check to use DEV-only data structure. This enables us to warn about more cases (e.g. useContext, useDebugValue) withou the need to add any overhead to production bundles.
* Throw in tests if work is done before emptying log
Test renderer already does this. Makes it harder to miss unexpected
behavior by forcing you to assert on every logged value.
* Convert ReactNoop tests to use jest matchers
The matchers warn if work is flushed while the log is empty. This is
the pattern we already follow for test renderer. I've used the same APIs
as test renderer, so it should be easy to switch between the two.
* Deprecate ref.setNativeProps in favor of ReactNative.setNativeProps
* Using a feature flag for the setNativeProps warning
* Removing extra line breaks
* Set the FB native feature flag to true
* Prettier
* Remove ReactNoop.flushDeferredPri and flushUnitsOfWork
Some of our older tests worked by counting how many times React checked
whether it should yield to the main thread, instead of something
publicly observable like how many times a component is rendered.
Our newer tests have converged on a style where we push into a log and
make assertions on the log. This pattern is less coupled to the
implementation while still being sufficient to test performance
optimizations, like resuming (whenever we add that back).
This commit removes flushDeferredPri and flushUnitsOfWork and upgrades
the affected tests.
* Remove shouldYieldToRenderer indirection
This wrapper is no longer necessary.
As I prepare to refactor the Fiber scheduler, I've noticed some quirks
in our implementation. This PR addressed one of them.
---
There's no reason for a timed out Scheduler callback to check
`shouldYield`, because the value will always be false until the work
has completed. The `didTimeout` argument provides this information to
the callback so it can avoid the redundant checks.
React's existing check for whether a callback has timed out didn't make
any sense, but happened to work anyway. I don't think the wrongness of
the old implementation is observable via React APIs but it's
incoherent regardless.
* Adding ReactNative.setNativeProps that takes a ref
* Adding test for components rendered with Fabric with Paper's setNativeProps
* Fixing flow types
* Fix prettier
* Rename ReactNativeSetNativeProps.js to be more general
2019-02-20 23:20:42 -08:00
566 changed files with 64850 additions and 27332 deletions
* Add `<React.Profiler>` API for gathering performance measurements programmatically. ([@bvaughn](https://github.com/bvaughn) in [#15172](https://github.com/facebook/react/pull/15172))
* Remove `unstable_ConcurrentMode` in favor of `unstable_createRoot`. ([@acdlite](https://github.com/acdlite) in [#15532](https://github.com/facebook/react/pull/15532))
### React DOM
* Deprecate old names for the `UNSAFE_*` lifecycle methods. ([@bvaughn](https://github.com/bvaughn) in [#15186](https://github.com/facebook/react/pull/15186) and [@threepointone](https://github.com/threepointone) in [#16103](https://github.com/facebook/react/pull/16103))
* Deprecate `javascript:` URLs as a common attack surface. ([@sebmarkbage](https://github.com/sebmarkbage) in [#15047](https://github.com/facebook/react/pull/15047))
* Deprecate uncommon "module pattern" (factory) components. ([@sebmarkbage](https://github.com/sebmarkbage) in [#15145](https://github.com/facebook/react/pull/15145))
* Add support for the `disablePictureInPicture` attribute on `<video>`. ([@eek](https://github.com/eek) in [#15334](https://github.com/facebook/react/pull/15334))
* Add support for `onLoad` event for `<embed>`. ([@cherniavskii](https://github.com/cherniavskii) in [#15614](https://github.com/facebook/react/pull/15614))
* Add support for editing `useState` state from DevTools. ([@bvaughn](https://github.com/bvaughn) in [#14906](https://github.com/facebook/react/pull/14906))
* Add support for toggling Suspense from DevTools. ([@gaearon](https://github.com/gaearon) in [#15232](https://github.com/facebook/react/pull/15232))
* Warn when `setState` is called from `useEffect`, creating a loop. ([@gaearon](https://github.com/gaearon) in [#15180](https://github.com/facebook/react/pull/15180))
* Fix a memory leak. ([@paulshen](https://github.com/paulshen) in [#16115](https://github.com/facebook/react/pull/16115))
* Fix a crash inside `findDOMNode` for components wrapped in `<Suspense>`. ([@acdlite](https://github.com/acdlite) in [#15312](https://github.com/facebook/react/pull/15312))
* Fix pending effects from being flushed too late. ([@acdlite](https://github.com/acdlite) in [#15650](https://github.com/facebook/react/pull/15650))
* Fix incorrect argument order in a warning message. ([@brickspert](https://github.com/brickspert) in [#15345](https://github.com/facebook/react/pull/15345))
* Fix hiding Suspense fallback nodes when there is an `!important` style. ([@acdlite](https://github.com/acdlite) in [#15861](https://github.com/facebook/react/pull/15861) and [#15882](https://github.com/facebook/react/pull/15882))
* Slightly improve hydration performance. ([@bmeurer](https://github.com/bmeurer) in [#15998](https://github.com/facebook/react/pull/15998))
### React DOM Server
* Fix incorrect output for camelCase custom CSS property names. ([@bedakb](https://github.com/bedakb) in [#16167](https://github.com/facebook/react/pull/16167))
### React Test Utilities and Test Renderer
* Add `act(async () => ...)` for testing asynchronous state updates. ([@threepointone](https://github.com/threepointone) in [#14853](https://github.com/facebook/react/pull/14853))
* Add support for nesting `act` from different renderers. ([@threepointone](https://github.com/threepointone) in [#16039](https://github.com/facebook/react/pull/16039) and [#16042](https://github.com/facebook/react/pull/16042))
* Warn in Strict Mode if effects are scheduled outside an `act()` call. ([@threepointone](https://github.com/threepointone) in [#15763](https://github.com/facebook/react/pull/15763) and [#16041](https://github.com/facebook/react/pull/16041))
* Warn when using `act` from the wrong renderer. ([@threepointone](https://github.com/threepointone) in [#15756](https://github.com/facebook/react/pull/15756))
## 16.8.6 (March 27, 2019)
### React DOM
* Fix an incorrect bailout in `useReducer()`. ([@acdlite](https://github.com/acdlite) in [#15124](https://github.com/facebook/react/pull/15124))
* Fix iframe warnings in Safari DevTools. ([@renanvalentin](https://github.com/renanvalentin) in [#15099](https://github.com/facebook/react/pull/15099))
* Warn if `contextType` is set to `Context.Consumer` instead of `Context`. ([@aweary](https://github.com/aweary) in [#14831](https://github.com/facebook/react/pull/14831))
* Warn if `contextType` is set to invalid values. ([@gaearon](https://github.com/gaearon) in [#15142](https://github.com/facebook/react/pull/15142))
## 16.8.5 (March 22, 2019)
### React DOM
* Don't set the first option as selected in select tag with `size` attribute. ([@kulek1](https://github.com/kulek1) in [#14242](https://github.com/facebook/react/pull/14242))
* Improve the `useEffect(async () => ...)` warning message. ([@gaearon](https://github.com/gaearon) in [#15118](https://github.com/facebook/react/pull/15118))
* Improve the error message sometimes caused by duplicate React. ([@jaredpalmer](https://github.com/jaredpalmer) in [#15139](https://github.com/facebook/react/pull/15139))
### React DOM Server
* Improve the `useLayoutEffect` warning message when server rendering. ([@gaearon](https://github.com/gaearon) in [#15158](https://github.com/facebook/react/pull/15158))
### React Shallow Renderer
* Fix `setState` in shallow renderer to work with Hooks. ([@gaearon](https://github.com/gaearon) in [#15120](https://github.com/facebook/react/pull/15120))
* Fix shallow renderer to support `React.memo`. ([@aweary](https://github.com/aweary) in [#14816](https://github.com/facebook/react/pull/14816))
* Fix shallow renderer to support Hooks inside `forwardRef`. ([@eps1lon](https://github.com/eps1lon) in [#15100](https://github.com/facebook/react/pull/15100))
## 16.8.4 (March 5, 2019)
### React DOM and other renderers
- Fix a bug where DevTools caused a runtime error when inspecting a component that used a `useContext` hook. ([@bvaughn](https://github.com/bvaughn) in [#14940](https://github.com/facebook/react/pull/14940))
## 16.8.3 (February 21, 2019)
### React DOM
* Fix a bug that caused inputs to behave incorrectly in UMD builds. ([@gaearon](https://github.com/gaearon) in [#14914](https://github.com/facebook/react/pull/14914))
* Fix a bug that caused render phase updates to be discarded. ([@gaearon](https://github.com/gaearon) in [#14852](https://github.com/facebook/react/pull/14852))
### React DOM Server
* Unwind the context stack when a stream is destroyed without completing, to prevent incorrect values during a subsequent render. ([@overlookmotel](https://github.com/overlookmotel) in [#14706](https://github.com/facebook/react/pull/14706/))
### ESLint Plugin for React Hooks
* Add a new recommended `exhaustive-deps` rule. ([@gaearon](https://github.com/gaearon) in [#14636](https://github.com/facebook/react/pull/14636))
<p><b>IMPORTANT:</b> This test may be flaky if other tests have been run in this js instance. To get a clean test refresh the page before running test 9</p>
<buttononClick="runTestNine()">Run Test 9</button>
<p>Runs scheduled JS work for 99% of the frame time when nothing else is using the thread.</p>
<p><b>NOTE:</b> Try this test both when nothing else is running and when something is using the compositor thread in another visible tab with video or <ahref="https://www.shadertoy.com/view/MtffDX">WebGL content</a> (Shift+Click).</p>
<buttononClick="runTestTen()">Run Test 10</button>
<p>Runs scheduled JS work more than 95% of the frame time when inserting DOM nodes.</p>
<p><b>NOTE:</b> Try this test both when nothing else is running and when something is using the compositor thread in another visible tab with video or <ahref="https://www.shadertoy.com/view/MtffDX">WebGL content</a> (Shift+Click).</p>
<buttononClick="runTestEleven()">Run Test 11</button>
This is a demo application based on [Dan Abramov's](https://github.com/gaearon) recent [JSConf Iceland talk](https://reactjs.org/blog/2018/03/01/sneak-peek-beyond-react-16.html) about React.
It depends on a local build of React and enables us to easily test async and "suspense" APIs in a more "real world app" like context.
## Can I use this code in production?
No. The APIs being tested here are unstable and some of them have still not been released to NPM. For now, this fixture is only a test harness.
@@ -28,7 +28,8 @@ Then add it to your ESLint configuration:
],
"rules":{
// ...
"react-hooks/rules-of-hooks":"error"
"react-hooks/rules-of-hooks":"error",
"react-hooks/exhaustive-deps":"warn"
}
}
```
@@ -37,6 +38,8 @@ Then add it to your ESLint configuration:
Please refer to the [Rules of Hooks](https://reactjs.org/docs/hooks-rules.html) documentation and the [Hooks FAQ](https://reactjs.org/docs/hooks-faq.html#what-exactly-do-the-lint-rules-enforce) to learn more about this rule.
For feedback about the `exhaustive-deps` rule, please post in [this thread](https://github.com/facebook/react/issues/14920).
"description":"React ART is a JavaScript library for drawing vector graphics using React. It provides declarative and reactive bindings to the ART library. Using the same declarative API you can render the output to either Canvas, SVG or VML (IE8).",
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