This is a follow up on https://github.com/facebook/react/pull/25592
There is another condition Offscreen calls
`recursivelyTraverseDisappearLayoutEffects` when it shouldn't. Offscreen
may be nested. When nested Offscreen is hidden, it should only unmount
layout effects if it meets following conditions:
1. This is an update, not first mount.
2. This Offscreen was hidden before.
3. No ancestor Offscreen is hidden.
Previously, we were not accounting for the third condition.
I don't think we need this anymore. It was added originally because
RootSuspended would take priority over RootSuspendedWithDelay. But we've
since changed it: any "bad" fallback state is permitted to block a
"good" fallback state.
The other status flags that this check used to account for are
RootDidNotComplete and RootFatalErrored:
- RootFatalErrored is like an invariant violation, it means something
went really wrong already and we can't recover from it
- RootCompleted and RootDidNotComplete are only set at the very end of
the work loop, there's no way for renderDidSuspendDelayIfPossible to
sneak in after that (at least none that I can think of — it's only
called from the render phase)
So I think we can just delete this.
It's entirely possible there's some scenario I haven't considered,
though, which is why I'm submitting this change as its own PR. To
preserve the ability to bisect to it later.
type validateDOMNesting
move `isHostResourceType` to ReactDOMHostConfig
type `AncestorInfo`
refactor `resourceFormOnly` into `ancestorInfo.containerTagInScope`
provide hostContext from reconciler
Makes it slightly more blazing.
No host config actually uses null as any useful and we use this as a
placeholder value anyway. It's also better for perf since it doesn't let
two different hidden classes pass around. It's also a magic place holder
that triggers error if we do try to access anything from it.
Initial draft. I need to test this more.
If a promise is passed to `use`, but the I/O isn't cached, we should
still be able to unwrap it.
This already worked in Server Components, and during SSR.
For Fiber (in the browser), before this fix the state would get lost
between attempts unless the promise resolved immediately in a microtask,
which requires IO to be cached. This was due to an implementation quirk
of Fiber where the state is reset as soon as the stack unwinds. The
workaround is to suspend the entire Fiber work loop until the promise
resolves.
The Server Components and SSR runtimes don't require a workaround: they
can maintain multiple parallel child tasks and reuse the state
indefinitely across attempts. That's ideally how Fiber should work, too,
but it will require larger refactor.
The downside of our approach in Fiber is that it won't "warm up" the
siblings while you're suspended, but to avoid waterfalls you're supposed
to hoist data fetches higher in the tree regardless. But we have other
ideas for how we can add this back in the future. (Though again, this
doesn't affect Server Components, which already have the ideal
behavior.)
`wasHidden` is evaluted to false if `current` is null. This means
Offscreen has never been shown but this code assumes it is going from
'visible' to 'hidden' and unmounts layout effects.
To fix this, only unmount layout effects if `current` is not null.
I'm not able to repro this problem or write unit test for it. I see this
crash bug in production test.
The problem with repro is that if Offscreen starts as hidden, it's
render is deferred and current is no longer null.
Pure refactor, no change in behavior.
Extracts the logic for detecting whether a suspended component will
result in a "bad" Suspense fallback into a helper function. An example
of a bad Suspense fallback is one that causes already-visible content
to disappear.
I want to reuse this same logic in the work loop, too.
Refactors the logic for handling when the work loop is suspended into
separate functions for replaying versus unwinding. This allows us to
hoist certain checks into the caller.
For example, when rendering due to flushSync, we will always unwind the
stack without yielding the microtasks.
No intentional behavior change in this commit.
This is a pure refactor, no change to behavior.
When a component throws, the work loop can handle that in one of several
ways — unwind immediately, wait for microtasks, and so on. I'm about
to add another one, too. So I've changed the variable that tracks
whether the work loop is suspended from a boolean
(workInProgressIsSuspended) to an enum (workInProgressSuspendedReason).
In Strict Mode, during development, user functions are double invoked to
help detect side effects. Currently, the way we implement this is to
completely discard the first pass and start over. Theoretically this
should be fine because components are idempotent. However, it's a bit
tricky to get right because our implementation (i.e. `renderWithHooks`)
is not completely idempotent with respect to internal data structures,
like the work-in-progress fiber. In the past we've had to be really
careful to avoid subtle bugs — for example, during the initial mount,
`setState` functions are bound to the particular hook instances that
were created during that render. If we compute new hook instances, we
must also compute new children, and they must correspond to each other.
This commit addresses a similar issue that came up related to `use`:
when something suspends, `use` reuses the promise that was passed during
the first attempt. This is itself a form of memoization. We need to be
able to memoize the reactive inputs to the `use` call using a hook (i.e.
`useMemo`), which means, the reactive inputs to `use` must come from the
same component invocation as the output.
The solution I've chosen is, rather than double invoke the entire
`renderWithHook` function, we should double invoke each individual user
function. It's a bit confusing but here's how it works:
We will invoke the entire component function twice. However, during the
second invocation of the component, the hook state from the first
invocation will be reused. That means things like `useMemo` functions
won't run again, because the deps will match and the memoized result
will be reused.
We want memoized functions to run twice, too, so account for this, user
functions are double invoked during the *first* invocation of the
component function, and are *not* double invoked during the second
incovation:
- First execution of component function: user functions are double
invoked
- Second execution of component function (in Strict Mode, during
development): user functions are not double invoked.
It's hard to explain verbally but much clearer when you run the test
cases I've added.
The old (unstable) mechanism for suspending was to throw a promise. The
purpose of throwing is to interrupt the component's execution, and also
to signal to React that the interruption was caused by Suspense as
opposed to some other error.
A flaw is that throwing is meant to be an implementation detail — if
code in userspace catches the promise, it can lead to unexpected
behavior.
With `use`, userspace code does not throw promises directly, but `use`
itself still needs to throw something to interrupt the component and
unwind the stack.
The solution is to throw an internal error. In development, we can
detect whether the error was caught by a userspace try/catch block and
log a warning — though it's not foolproof, since a clever user could
catch the object and rethrow it later.
The error message includes advice to move `use` outside of the try/catch
block.
I did not yet implement the warning in Flight.
There are two different switch statements that we use to unwrap a
`use`-ed promise, but there really only needs to be one. This was a
factoring artifact that arose because I implemented the yieldy `status`
instrumentation thing before I implemented `use` (for promises that are
thrown directly during render, which is the old Suspense pattern that
will be superseded by `use`).
This is a refactor to track the array of thenables that is preserved
across replays in the work loop instead of the Thenable module.
The reason is that I'm about to add additional state to the Thenable
module that is specific to a particular attempt — like the current
index — and is reset between replays. So it's helpful to keep the two
kinds of state separate so it's clearer which state gets reset when.
The array of thenables is not reset until the work-in-progress either
completes or unwinds.
This also makes the structure more similar to Fizz and Flight.
Adds some clarifying warnings when you render a component that is almost
a resource but isn't and the element was rendered outside the main
document tree (outside of `<body>` or `<head>`
To derisk the rollout of `use`, and simplify the implementation, this
reverts the yield-to-microtasks behavior for promises that are thrown
directly (as opposed to being unwrapped by `use`).
We may add this back later. However, the plan is to deprecate throwing a
promise directly and migrate all existing Suspense code to `use`, so the
extra code probably isn't worth it.
Stacked on #25508
This PR adds meta tags as a resource type.
metas are classified in the following priority
1. charset
2. http-equiv
3. property
4. name
5. itemprop
when using property, there is special logic for og type properties where
a `property="og:image:height"` following a `property="og:image"` will
inherit the key of the previous tag. this relies on timing effects to
stay consistent so when mounting new metas it is important that if
structured properties are being used all members of a structure mount
together. This is similarly true for arrays where the implicit
sequential order defines the array structure. if you need an array you
need to mount all array members in the same pass.
With the `react-dom/server-rendering-stub` you can import `react-dom` in
RSC so that you can call `preload` and `preinit` but if you don't alias
it, then requiring it breaks because we React.Component which doesn't
exist in the react subset.
Adds a category of Resources of type `head` which will be used to track
the tags that go into the <head>
Currently only implements for `<title>`.
titles are keyed off their textContent so each time the title changes a
new resource will be created. Currently insertion is done by prepending
in the <head>. The argument here is that the newest title should "win"
if there are multiple rendered. This also helps when a navigation or
update causes a server rendered title to hang around but it is not the
most recent one.
`use` can avoid suspending on already resolved data by yielding to
microtasks. In a real, browser environment, we do this by scheduling a
platform task (i.e. postTask).
In a test environment, tasks are scheduled on a special internal queue
so that they can be flushed by the `act` testing API. So we need to add
support for this in `act`.
This behavior only works if you `await` the thenable returned by the
`act` call. We currently do not require that users do this. So I added a
warning, but it only fires if `use` was called. The old Suspense pattern
will not trigger a warning. This is to avoid breaking existing tests
that use Suspense.
The implementation of `act` has gotten extremely complicated because of
the subtle changes in behavior over the years, and our commitment to
maintaining backwards compatibility. We really should consider being
more restrictive in a future major release.
The changes are a bit confusing so I did my best to add inline comments
explaining how it works.
## Test plan
I ran this against Facebook's internal Jest test suite to confirm
nothing broke
* Add fetch instrumentation in cached contexts
* Avoid unhandled rejection errors for Promises that we intentionally ignore
In the final passes, we ignore the newly generated Promises and use
the previous ones. This ensures that if those generate errors, that we
intentionally ignore those.
* Add extra fetch properties if there were any
* [useEvent] Non-stable function identity
Since useEvent shouldn't go in the dependency list of whatever is
consuming it (which is enforced by the fact that useEvent functions are
always locally created and never passed by reference), its identity
doesn't matter. Effectively, this PR is a runtime assertion
that you can't rely on the return value of useEvent to be stable.
* Test: Events should see latest bindings
The key feature of useEvent that makes it different from useCallback
is that events always see the latest committed values. There's no such
thing as a "stale" event handler.
* Don't queue a commit effect on mount
* Inline event function wrapping
- Inlines wrapping of the callback
- Use a mutable ref-style object instead of a callable object
- Fix types
Co-authored-by: Andrew Clark <git@andrewclark.io>
* Facebook -> Meta in copyright
rg --files | xargs sed -i 's#Copyright (c) Facebook, Inc. and its affiliates.#Copyright (c) Meta Platforms, Inc. and affiliates.#g'
* Manual tweaks
* float enhance!!!
Support preinit as script
Support resources from async scripts
Support saving the precedence place when rendering the shell
There was a significant change to the flushing order of resources which follows the general principal of...
1. stuff that blocks display
2. stuff that we know will be used
3. stuff that was explicitly preloaded
As a consequence if you preinit a style now it won't automatically flush in the shell unless you actually depend on it in your tree. To avoid races with precedence order we now emit a tag that saves the place amongst the precedence hierarchy so late insertions still end up where they were intended
There is also a novel hydration pathway for certain tags. If you render an async script with an onLoad or onError it will always treat it like an insertion rather than a hydration.
* restore preinit style flushing behavior and nits
Fixes a bug that happens when you suspend in the shell (the part of the
tree that is not wrapped in a Suspense boundary) during a
discrete update.
There were two underyling issues. One was just a mistake:
RootDidNotComplete needs to be handled in both renderRootConcurrent and
renderRootSync, but it was only handled in renderRootConcurrent. I did
it this way because I thought this path was unreachable during a sync
update, but I neglected to consider that renderRootSync is sometimes
called for non-concurrent lanes, like when recovering from an error, or
patching up a mutation to an external store.
After I fixed that oversight, the other issue is that we intentionally
error if the shell suspends during a sync update. The idea was that you
should either wrap the tree in a Suspense boundary, or you should mark
the update as a transition to allow React to suspend.
However, this did not take into account selective hydration, which can
force a sync render before anything has even committed. There's no way
in that case to wrap the update in startTransition.
Our solution for now is to remove the error that happens when you
suspend in the shell during a sync update — even for discrete updates.
We will likely revisit this in the future. One appealing possibility is
to commit the whole root in an inert state, as if it were a hidden
Offscreen tree.
Co-authored-by: Sebastian Markbåge <sebastian@calyptus.eu>
Co-authored-by: Sebastian Markbåge <sebastian@calyptus.eu>
* Missing Hooks
* Remove www forks. These can use __SECRET... instead.
* Move cache to separate dispatcher
These will be available in more contexts than just render.
In #24967, I changed the behavior of Offscreen so that passive effects
are not fired when the tree is hidden. I accidentally applied this
behavior to the old LegacyHidden API, too, which is a deprecated
internal-only type that www has been using while they wait for Offscreen
to be ready.
This fixes LegacyHidden so that the effects do not get deferred, like
before. The new behavior still remains in the Offscreen API, which is
experimental and not currently in use in www.
* track resources in different roots separately
* flow types
* add test demonstrating portals deep into shadowRoots
* revert hostcontext changes
* lints
* funge style cache key a la ReactDOMComponentTree
* hide hacks in componentTree
The existential type `*` was deprecated and a codemod provided to replace it. Ran that and did some manual fixups:
```sh
node_modules/.bin/flow codemod replace-existentials --write .
```
ghstack-source-id: 4c98b8db6a
Pull Request resolved: https://github.com/facebook/react/pull/25416
- method unbinding is no longer supported in Flow for soundness, this added a bunch of suppressions
- Flow now prevents objects to be supertypes of interfaces/classes
ghstack-source-id: d7749cbad8
Pull Request resolved: https://github.com/facebook/react/pull/25412
This upgrade made more expressions invalidate refinements. In some
places this lead to a large number of suppressions that I automatically
suppressed and should be followed up on when the code is touched.
I think most of them might require either manual annotations or moving
a value into a const to allow refinement.
ghstack-source-id: a45b40abf0
Pull Request resolved: https://github.com/facebook/react/pull/25410
This was a large upgrade that removed "classic mode" and made "types first" the only option.
Most of the needed changes have been done in previous PRs, this just fixes up the last few instances.
ghstack-source-id: 9612d95ba4
Pull Request resolved: https://github.com/facebook/react/pull/25408
This contains one code change, renaming the local function `ChildReconciler` to `createChildReconciler` as it's called as a function, not a constructor and to free up the name for the return value.
* [Fizz/Float] Float for stylesheet resources
This commit implements Float in Fizz and on the Client. The initial set of supported APIs is roughly
1. Convert certain stylesheets into style Resources when opting in with precedence prop
2. Emit preloads for stylesheets and explicit preload tags
3. Dedupe all Resources by href
4. Implement ReactDOM.preload() to allow for imperative preloading
5. Implement ReactDOM.preinit() to allow for imperative preinitialization
Currently supports
1. style Resources (link rel "stylesheet")
2. font Resources (preload as "font")
later updates will include support for scripts and modules
Aurélien Chivot-Buhler
Samuel Susla
Andrew Clark
Josh Story
Sebastian Markbåge
laurenandAndrew Clark
c0dedanceandJan Kassens
Joseph Savona
Jan Kassens