The `resumeElement` function wasn't actually doing the correct thing
because it was resuming the element itself but what the child slot means
is that we're supposed to resume in the direct child of the element.
This is difficult to check for since it's all the possible branches that
the element can render into, so instead we just check this in
renderNode. It means the hottest path always checks the task which is
unfortunate.
And also, resuming using the correct nextSegmentId.
Fixes two bugs surfaced by this test.
---------
Co-authored-by: Josh Story <josh.c.story@gmail.com>
DiffTrain build for [a6ed60a8eb](https://github.com/facebook/react/commit/a6ed60a8eb0626e5f84d0bdbb62c0b61219150d3)
I do this by simply renaming the secret export name in the "subset"
bundle and this renamed version is what the FlightServer uses.
This requires us to be more diligent about always using the correct
instance of "react" in our tests so there's a bunch of clean up for
that.
DiffTrain build for [c7ba8c0988](https://github.com/facebook/react/commit/c7ba8c098889b6dc47fa9c807bbba3975a658584)
This adds a regression test and fix for a case where a sync update
triggers selective hydration, which then leads to a "Maximum update
depth exceeded" error, even though there was only a single update. This
happens when a single sync update flows into many sibling dehydrated
Suspense boundaries.
This fix is, if a commit was the result of selective hydration, we
should not increment the nested update count, because those renders
conceptually are not updates.
Ideally, they wouldn't even be in a separate commit — we should be able
to hydrate a tree and apply an update on top of it within the same
render phase. We could do this once we implement resumable context
stacks.
DiffTrain build for [d900fadbf9](https://github.com/facebook/react/commit/d900fadbf9017063fecb2641b7e99303b82a6f17)
`performSyncWorkOnRoot` has only a single caller, and the caller already
computes the next lanes (`getNextLanes`) before deciding to call the
function. So we can pass them as an argument instead of computing the
lanes again.
There was already a TODO comment about this, but it was mostly perf
related. However, @rickhanlonii noticed a discrepancy where the inner
`getNextLanes` call was not being passed the current work-in- progress
lanes. Usually this shouldn't matter because there should never be
work-in-progress sync work; it should finish immediately. There is one
case I'm aware of where we exit the work loop without finishing a sync
render, which is selective hydration, but even then it should switch to
the sync hydration lane, not the normal sync lane. So something else is
probably going on. I suspect it might be related to the
`enableUnifiedSyncLane` experiment.
This is likely related to a regression found internally at Meta. We're
still working on getting a proper regression test; I can come up with a
contrived one but I'm not confident it'll be the same as the actual
regression until we get a better repro.
DiffTrain build for [13d0225c7d](https://github.com/facebook/react/commit/13d0225c7d4715d98772a85d8deb26d244921287)
As agreed, we're removing Server Context. This was never official
documented.
We've found that it's not that useful in practice. Often the better
options are:
- Read things off the url or global scope like params or cookies.
- Use the module system for global dependency injection.
- Use `React.cache()` to dedupe multiple things instead of computing
once and passing down.
There are still legit use cases for Server Context but you have to be
very careful not to pass any large data, so in generally we recommend
against it anyway.
Yes, prop drilling is annoying but it's not impossible for the cases
this is needed. I would personally always pick it over Server Context
anyway.
Semantically, Server Context also blocks object deduping due to how it
plays out with Server Components that can't be deduped. This is much
more important feature.
Since it's already in canary along with the rest of RSC, we're adding a
warning for a few versions before removing completely to help migration.
---------
Co-authored-by: Josh Story <josh.c.story@gmail.com>
DiffTrain build for [1ebedbec2b](https://github.com/facebook/react/commit/1ebedbec2bec08e07c286ea6c3cff62737a0fd3a)
Currently when we SSR a Flight response we do not emit any resources for
module imports. This means that when the client hydrates it won't have
already loaded the necessary scripts to satisfy the Imports defined in
the Flight payload which will lead to a delay in hydration completing.
This change updates `react-server-dom-webpack` and
`react-server-dom-esm` to emit async script tags in the head when we
encounter a modules in the flight response.
To support this we need some additional server configuration. We need to
know the path prefix for chunk loading and whether the chunks will load
with CORS or not (and if so with what configuration).
DiffTrain build for [701ac2e572](https://github.com/facebook/react/commit/701ac2e57290f913502c6012c15e815f412f84b7)
Refactors Resources to have a more compact and memory efficient
struture. Resources generally are just an Array of chunks. A resource is
flushed when it's chunks is length zero. A resource does not have any
other state.
Stylesheets and Style tags are different and have been modeled as a unit
as a StyleQueue. This object stores the style rules to flush as part of
style tags using precedence as well as all the stylesheets associated
with the precedence. Stylesheets still need to track state because it
affects how we issue boundary completion instructions. Additionally
stylesheets encode chunks lazily because we may never write them as html
if they are discovered late.
The preload props transfer is now maximally compact (only stores the
props we would ever actually adopt) and only stores props for
stylesheets and scripts because other preloads have no resource
counterpart to adopt props into. The ResumableState maps that track
which keys have been observed are being overloaded. Previously if a key
was found it meant that a resource already exists (either in this render
or in a prior prerender). Now we discriminate between null and object
values. If map value is null we can assume the resource exists but if it
is an object that represents a prior preload for that resource and the
resource must still be constructed.
DiffTrain build for [49eba01930](https://github.com/facebook/react/commit/49eba01930e9e1f331b34967fca65d5a0ba62846)
This fixes so that you can postpone in a fallback. This postpones the
parent boundary. I track the fallbacks in a separate replay node so that
when we resume, we can replay the fallback itself and finish the
fallback and then possibly later the content. By doing this we also
ensure we don't complete the parent too early since now it has a render
task on it.
There is one case that this surfaces that isn't limited to
prerender/resume but also render/hydrateRoot. I left todos in the tests
for this.
If you postpone in a fallback, and suspend in the content but eventually
don't postpone in the content then we should be able to just skip
postponing since the content rendered and we no longer need the
fallback. This is a bit of a weird edge case though since fallbacks are
supposed to be very minimal.
This happens because in both cases the fallback starts rendering early
as soon as the content suspends. This also ensures that the parent
doesn't complete early by increasing the blocking tasks. Unfortunately,
the fallback will irreversibly postpone its parent boundary as soon as
it hits a postpone.
When you suspend, the same thing happens but we typically deal with this
by doing a "soft" abort on the fallback since we don't need it anymore
which unblocks the parent boundary. We can't do that with postpone right
now though since it's considered a terminal state.
I think I'll just leave this as is for now since it's an edge case but
it's an annoying exception in the model. Makes me feel I haven't quite
nailed it just yet.
DiffTrain build for [bff6be8eb1](https://github.com/facebook/react/commit/bff6be8eb1d77980c13f3e01be63cb813a377058)
We currently abort a stream either it's explicitly told to abort (e.g.
by an abortsignal). In this case we still finish writing what we have as
well as instructions for the client about what happened so it can
trigger fallback cases and log appropriately.
We also abort a request if the stream itself cancels. E.g. if you can't
write anymore. In this case we should not write anything to the outgoing
stream since it's supposed to be closed already now. However, we should
still abort the request so that more work isn't performed and so that we
can log the reason for it to the onError callback.
We should also not do any work after aborting.
There we need to stop the "flow" of bytes - so I call stopFlowing in the
cancel case before aborting.
The tests were testing this case but we had changed the implementation
to only start flowing at initial read (pull) instead of start like we
used to. As a result, it was no longer covering this case. We have to
call reader.read() in the tests to start the flow so that we need to
cancel it.
We also were missing a final assertion on the error logs and since we
were tracking them explicitly the extra error was silenced.
DiffTrain build for [d9e00f795b](https://github.com/facebook/react/commit/d9e00f795b77676fb14f2a3c6f421f48f73bec2a)
The key is that instead of storing different tags of resumable points,
we just store if a replay node has any resumable slots and if that's at
the root `number` or if it has resumable slots by index.
This is a simpler and more compact format because we don't have to
separate the three Resume forms.
This helps deal with Postpone in fallbacks because it doesn't just
double all the cases.
DiffTrain build for [47fed6961f](https://github.com/facebook/react/commit/47fed6961f79e8c8388f5f11fe1a531b194bb4af)
Fixes#26876, I think. Review each commit separately (all assertions
pass in main already, except the last assertInputTrackingIsClean in
"should control radio buttons").
I'm actually a little confused on two things here:
* All the isCheckedDirty assertions are true. But I don't think we set
.checked unconditionally? So how does this happen?
* https://github.com/facebook/react/issues/26876#issuecomment-1611662862
claims that
https://github.com/facebook/react/compare/d962f35ca...1f248bdd7 contains
the faulty change, but it doesn't appear to change the restoration logic
that I've touched here. (One difference outside restoration is that
updateProperties did previously set `.checked` when `nextProp !==
lastProp` whereas the new logic in updateInput is to set it when
`node.checked !== !!checked`.)
But it seems to me like we need this call here anyway, and if it fixes
it then it fixes it? I think technically speaking we probably should do
all the updateInput() calls and then all the updateValueIfChanged()
calls—in particular I think if clicking A changed the checked radio
button from B to C then the code as I have it would be incorrect, but
that also seems unlikely so idk whether to care.
cc @zhengjitf @Luk-z who did some investigation on the original issue
DiffTrain build for [3c27178a2f](https://github.com/facebook/react/commit/3c27178a2f2c74f14d90613028e3929e1f06d830)
To support MPA-style form submissions, useFormState sends down a key
that represents the identity of the hook on the page. It's based on the
key path of the component within the React tree; for deeply nested
hooks, this keypath can become very long. We can hash the key to make it
shorter.
Adds a method called createFastHash to the Stream Config interface.
We're not using this for security or obfuscation, only to generate a
more compact key without sacrificing too much collision resistance.
- In Node.js builds, createFastHash uses the built-in crypto module.
- In Bun builds, createFastHash uses Bun.hash. See:
https://bun.sh/docs/api/hashing#bun-hash
I have not yet implemented createFastHash in the Edge, Browser, or FB
(Hermes) stream configs because those environments do not have a
built-in hashing function that meets our requirements. (We can't use the
web standard `crypto` API because those methods are async, and yielding
to the main thread is too costly to be worth it for this particular use
case.) We'll likely use a pure JS implementation in those environments;
for now, they just return the original string without hashing it. I'll
address this in separate PRs.
DiffTrain build for [2b3d582683](https://github.com/facebook/react/commit/2b3d5826836ac59f8446281976762d594e55d97e)
## Summary
Currently `ReactFizzServer.abort` allows you to pass in the a `reason`
error, which then gets passed to the `onError` handler for each task
that ends up getting aborted. This adds in the ability to pass down that
same `reason` error to `ReactDOMServerFB.abortStream` as well.
## How did you test this change?
Added a test case to ReactDOMServerFB-test.internal.js
DiffTrain build for [1f4936660d](https://github.com/facebook/react/commit/1f4936660dcaba2e5722013f0ad12d7369543a9f)
Moves writing queues to renderState.
We shouldn't need the resource tracking's value. We just need to know if
that resource has already been emitted. We can use a Set for this. To
ensure that set is directly serializable we can just use a
dictionary-like object with no value.
See individual commits for special cases.
DiffTrain build for [b775564d35](https://github.com/facebook/react/commit/b775564d35d6fe9f9acead0f380bbc86bb6bdd2c)
Originally the intension was to have React assign an ID to a user
rendered DOM node inside a `fallback` while it was loading. If there
already were an explicit `id` defined on the DOM element we would reuse
that one instead. That's why this was a DOM Config option and not just
built in to Fizz.
This became tricky since it can load late and so we'd have to transfer
it down and detect it only once it finished rendering and if there is no
DOM element it doesn't work anyway. So instead, what we do in practice
is to always use a `<template>` tag with the ID. This has the downside
of an extra useless node and shifting child CSS selectors.
Maybe we'll get around to fixing this properly but it might not be worth
it.
This PR just gets rid of the SuspenseBoundaryID concept and instead we
just use the same ID number as the root segment ID of the boundary to
refer to the boundary to simplify the implementation.
This also solves the problem that SuspenseBoundaryID isn't currently
serializable (although that's easily fixable by itself if necessary).
DiffTrain build for [2807d781a0](https://github.com/facebook/react/commit/2807d781a08db8e9873687fccc25c0f12b4fb3d4)
Based on #27385.
When we error or abort during replay, that doesn't actually error the
component that errored because that has already rendered. The error only
affects any child that is not yet completed. Therefore the error kind of
gets thrown at the resumable point.
The resumable point might be a hole in the replay path, in which case
throwing there errors the parent boundary just the same as if the replay
component errored. If the hole is inside a deeper Suspense boundary
though, then it's that Suspense boundary that gets client rendered. I.e.
the child boundary. We can still finish any siblings.
In the shell all resumable points are inside a boundary since we must
have finished the shell. Therefore if you error in the root, we just
simply just turn all incomplete boundaries into client renders.
DiffTrain build for [925c66a647](https://github.com/facebook/react/commit/925c66a6472a61e7174dabf6c697a9a320ebc170)
The idea for this check is that we shouldn't flush anything before we
flush the shell. That may or may not hold true in future formats like
RN.
It is a problem for resuming because with resuming it's possible to have
root tasks that are used for resuming but the shell was already flushed
so we can have completed boundaries before the shell has fully resumed.
What matters is whether the parent has already flushed or not.
It's not technically necessary to bail early because there won't be
anything in partialBoundaries or completedBoundaries because nothing
gets added there unless the parent has already flushed.
It's not exactly slow to have to check the length of three arrays so
it's probably not a big deal.
Flush partials in an early preamble needs further consideration
regardless.
DiffTrain build for [df061b3966](https://github.com/facebook/react/commit/df061b396644bb7c27ea76bb27ae09784ce6444b)
This forks Task into ReplayTask and RenderTask.
A RenderTask is the normal mode and it has a segment to write into.
A ReplayTask doesn't have a segment to write into because that has
already been written but instead it has a ReplayState which keeps track
of the next set of paths to follow. Once we hit a "Resume" node we
convert it into a RenderTask and continue rendering from there.
We can resume at either an Element position or a Slot position. An
Element pointing to a component doesn't mean we resume that component,
it means we resume in the child position directly below that component.
Slots are slots inside arrays.
Instead of statically forking most paths, I kept using the same path and
checked for the existence of a segment or replay state dynamically at
runtime.
However, there's still quite a bit of forking here like retryRenderTask
and retryReplayTask. Even in the new forks there's a lot of duplication
like resumeSuspenseBoundary, replaySuspenseBoundary and
renderSuspenseBoundary. There's opportunity to simplify this a bit.
DiffTrain build for [a5fc797db1](https://github.com/facebook/react/commit/a5fc797db14c6e05d4d5c4dbb22a0dd70d41f5d5)
Adds a separate entry point for the react-dom package when it's accessed
from a Server Component environment, using the "react-server" export
condition.
When you're inside a Server Component module, you won't be able to
import client-only APIs like useState. This applies to almost all React
DOM exports, except for Float ones like preload.
DiffTrain build for [2d2f2af29b](https://github.com/facebook/react/commit/2d2f2af29bc3175530a158bc90189fc6f12f7855)
The permalink option of useFormState controls which page the form is
submitted to during an MPA form submission (i.e. a submission that
happens before hydration, or when JS is disabled). If the same
useFormState appears on the resulting page, and the permalink option
matches, it should receive the form state from the submission despite
the fact that the keypaths do not match.
So the logic for whether a form state instance is considered a match is:
- Both instances must be passed the same action signature
- If a permalink is provided, the permalinks must match.
- If a permalink is not provided, the keypaths must match.
Currently, if there are multiple matching useFormStates, they will all
match and receive the form state. We should probably only match the
first one, and/or warn when this happens. I've left this as a TODO for
now, pending further discussion.
DiffTrain build for [caa716d50b](https://github.com/facebook/react/commit/caa716d50bdeef3a1ac5e3e0cfcc14f4d91f2028)
Typically we assign IDs lazily when flushing to minimize the ids we have
to assign and we try to maximize inlining.
When we prerender we could always flush into a buffer before returning
but that's not actually what we do right now. We complete rendering
before returning but we don't actually run the flush path until someone
reads the resulting stream. We assign IDs eagerly when something
postpone so that we can refer to those ids in the holes without flushing
first.
This leads to some interesting conditions that needs to consider this.
This PR also deals with rootSegmentId which is the ID of the segment
that contains the body of a Suspense boundary. The boundary needs to
know this in addition to the Suspense Boundary's ID to know how to
inject the root segment into the boundary.
Why is the suspense boundary ID and the rootSegmentID just not the same
ID? Why don't segments and suspense boundary not share ID namespace?
That's a good question and I don't really remember. It might not be a
good reason and maybe they should just be the same.
DiffTrain build for [a6e4791b11](https://github.com/facebook/react/commit/a6e4791b11816374d015eb4531a82e6cf209c7f2)
During an MPA form submission, useFormState should only reuse the form
state if same action is passed both times. (We also compare the key
paths.)
We compare the identity of the inner closure function, disregarding the
value of the bound arguments. That way you can pass an inline Server
Action closure:
```js
function FormContainer({maxLength}) {
function submitAction(prevState, formData) {
'use server'
if (formData.get('field').length > maxLength) {
return { errorMsg: 'Too many characters' };
}
// ...
}
return <Form submitAction={submitAction} />
}
```
DiffTrain build for [95c9554bc7](https://github.com/facebook/react/commit/95c9554bc72813b0ee2b028774bb7cf0482887ba)
If a Server Action is passed to useFormState, the action may be
submitted before it has hydrated. This will trigger a full page
(MPA-style) navigation. We can transfer the form state to the next page
by comparing the key path of the hook instance.
`ReactServerDOMServer.decodeFormState` is used by the server to extract
the form state from the submitted action. This value can then be passed
as an option when rendering the new page. It must be passed during both
SSR and hydration.
```js
const boundAction = await decodeAction(formData, serverManifest);
const result = await boundAction();
const formState = decodeFormState(result, formData, serverManifest);
// SSR
const response = createFromReadableStream(<App />);
const ssrStream = await renderToReadableStream(response, { formState })
// Hydration
hydrateRoot(container, <App />, { formState });
```
If the `formState` option is omitted, then the state won't be
transferred to the next page. However, it must be passed in both places,
or in neither; misconfiguring will result in a hydration mismatch.
(The `formState` option is currently prefixed with `experimental_`)
DiffTrain build for [612b2b6601](https://github.com/facebook/react/commit/612b2b6601abb844248c384d1e288bb824b180b7)
This field was not being initialized. Although the property is part of
the Flow type, the type error wasn't caught because the constructor
itself is not covered by Flow, which is unfortunate. (I assume this is
related to the dev-only componentStack property.)
DiffTrain build for [69be472c11](https://github.com/facebook/react/commit/69be472c11231056d297a7b73dd0b121905606d3)
Currently, if a component suspends, the keyPath has already been
modified to include the identity of the component itself; the path is
set before the component body is called (akin to the begin phase in
Fiber). An accidental consequence is that when the promise resolves and
component is retried, the identity gets appended to the keyPath again,
leading to a duplicate node in the path.
To address this, we should only modify contexts after any code that may
suspend. For maximum safety, this should occur as late as possible:
right before the recursive renderNode call, before the children are
rendered.
I did not add a test yet because there's no feature that currently
observes it, but I do have tests in my other WIP PR for useFormState:
#27321
DiffTrain build for [d07921eeda](https://github.com/facebook/react/commit/d07921eeda62613bfcf52ecdb66322db26393567)
There's a subtle difference if you suspend before the first array or
after. In Fiber, we don't deal with this because we just suspend the
parent and replay it if lazy() or Usable are used in its child slots. In
Fizz we try to optimize this a bit more and enable resuming inside the
component.
Semantically, it's different if you suspend/postpone before the first
child array or inside that child array. Because when you resume the
inner result might be another array and either that's part of the parent
path or part of the inner slot.
There might be more clever way of structuring this but I just use -1 to
indicate that we're not yet inside the array and is in the root child
position. If that renders an element, then that's just the same as the 0
slot.
We need to also encode this in the resuming. I called that resuming the
element or resuming the slot.
DiffTrain build for [7a3cb8f9cf](https://github.com/facebook/react/commit/7a3cb8f9cf43591afc74722ece9e3216ccc98128)
When Float was first developed the internal implementation and external
interface were the same. This is problematic for a few reasons. One, the
public interface is typed but it is also untrusted and we should not
assume that it is actually respected. Two, the internal implementations
can get called from places other than the the public interface and
having to construct an options argument that ends up being destructured
to process the request is computationally wasteful and may limit JIT
optimizations to some degree. Lastly, the wire format was not as
compressed as it could be and it was untyped.
This refactor aims to address that by separating the public interface
from the internal implementations so we can solve these challenges and
also make it easier to change Float in the future
* The internal dispatcher method preinit is now preinitStyle and
preinitScript.
* The internal dispatcher method preinitModule is now
preinitModuleScript in anticipation of different implementations for
other module types in the future.
* The wire format is explicitly typed and only includes options if they
are actually used omitting undefined and nulls.
* Some function arguments are not options even if they are optional. For
instance precedence can be null/undefined because we deafult it to
'default' however we don't cosnider this an option because it is not
something we transparently apply as props to the underlying instance.
* Fixes a problem with keying images in flight where srcset and sizes
were not being taken into account.
* Moves argument validation into the ReactDOMFloat file where it is
shared with all runtimes that expose these methods
* Fixes crossOrigin serialization to use empty string except when
'use-credentials'
DiffTrain build for [bbc8530ed7](https://github.com/facebook/react/commit/bbc8530ed7a67859583a7c990ac51cd39c7746e5)
It's possible to postpone a specific node and not using a wrapper
component. Therefore we encode the resumable slot as the index slot.
When it's a plain client component that postpones, it's encoded as the
child slot inside that component which is the one that's postponed
rather than the component itself.
Since it's possible for a child slot to suspend (e.g. React.lazy's
microtask in this case) retryTask might need to keep its index around
when it resolves.
DiffTrain build for [bb1d8d1667](https://github.com/facebook/react/commit/bb1d8d166799eb97892be6c7826179270ba283d0)
A planned feature of useFormState is that if the page load is the result
of an MPA-style form submission — i.e. a form was submitted before it
was hydrated, using Server Actions — the state of the hook should
transfer to the next page.
I haven't implemented that part yet, but as a prerequisite, we need some
way for Fizz to indicate whether a useFormState hook was rendered using
the "postback" state. That way we can do all state matching logic on the
server without having to replicate it on the client, too.
The approach here is to emit a comment node for each useFormState hook.
We use one of two comment types: `<!--F-->` for a normal useFormState
hook, and `<!--F!-->` for a hook that was rendered using the postback
state. React will read these markers during hydration. This is similar
to how we encode Suspense boundaries.
Again, the actual matching algorithm is not yet implemented — for now,
the "not matching" marker is always emitted.
We can optimize this further by not emitting any markers for a render
that is not the result of a form postback, which I'll do in subsequent
PRs.
DiffTrain build for [8b26f07a88](https://github.com/facebook/react/commit/8b26f07a883bb341c20283c0099bf5ee6f87bd1f)
img tags inside picture tags should not automatically be preloaded
because usually the img is a fallback. We will consider a more
comprehensive way of preloading picture tags which may require a
technique like using an inline script to construct the image in the
browser but for now we simply omit the preloads to avoid harming load
times by loading fallbacks.
DiffTrain build for [3566de59e2](https://github.com/facebook/react/commit/3566de59e2046e7e8478462375aaa71716f1095b)
Just moving some internal code around again.
I originally encoded what type of work using startRender vs
startPrerender. I had intended to do more forking of the work loop but
we've decided not to go with that strategy. It also turns out that
forking when we start working is actually too late because of a subtle
thing where you can call abort before work begins. Therefore it's
important that starting the work comes later.
DiffTrain build for [953cb02f6d](https://github.com/facebook/react/commit/953cb02f6de2a9f3eb52456b263e11f839584bc6)
To generate IDs for useId, we modify a context variable whenever
multiple siblings are rendered, or when a component includes a useId
hook.
When this happens, we must ensure that the context is reset properly on
unwind if something errors or suspends. When I originally implemented
this, I did this by wrapping the child's rendering with a try/finally
block. But a better way to do this is by using the non-destructive
renderNode path instead of renderNodeDestructive.
DiffTrain build for [ee7f9c9351](https://github.com/facebook/react/commit/ee7f9c9351f8902e07ceacf4234ef75e7e4ecd73)
This joins the static (prerender) builds with the server builds but
doesn't change the public entry points.
The idea of two separate bundles is that we'd have a specialized build
for Fizz just for the prerender that could do a lot more. However, in
practice the code is implemented with a dynamic check so it's in both.
It's also not a lot of code.
At the same time if you do have a set up that includes both the
prerender and the render in the same build output, this just doubles the
server bundle size for no reason.
So we might as well merge them into one build. However, I don't expose
the `prerender` from `/server`. Instead it's just exposed from the
public `/static` entry point. This leaves us with the option to go back
to separate builds later if it diverges more in the future.
DiffTrain build for [2c2bdd0ffe](https://github.com/facebook/react/commit/2c2bdd0ffe54df60201ee93b29de5cb7b93ff029)
This is basically the implementation for the prerender pass.
Instead of forking basically the whole implementation for prerender, I
just add a conditional field on the request. If it's `null` it behaves
like before. If it's non-`null` then instead of triggering client
rendered boundaries it triggers those into a "postponed" state which is
basically just a variant of "pending". It's supposed to be filled in
later.
It also builds up a serializable tree of which path can be followed to
find the holes. This is basically a reverse `KeyPath` tree.
It is unfortunate that this approach adds more code to the regular Fizz
builds but in practice. It seems like this side is not going to add much
code and we might instead just want to merge the builds so that it's
smaller when you have `prerender` and `resume` in the same bundle -
which I think will be common in practice.
This just implements the prerender side, and not the resume side, which
is why the tests have a TODO. That's in a follow up PR.
DiffTrain build for [b70a0d7022](https://github.com/facebook/react/commit/b70a0d70224ceb4e277bd8ac535a2caafa5c075a)
When the `permalink` option is passed to `useFormState`, and the form is
submitted before it has hydrated, the permalink will be used as the
target of the form action, enabling MPA-style form submissions.
(Note that submitting a form without hydration is a feature of Server
Actions; it doesn't work with regular client actions.)
It does not have any effect after the form has hydrated.
DiffTrain build for [ddff504695](https://github.com/facebook/react/commit/ddff504695f33c19e8c0792bff82bd8f8b8f7c05)
This implements useFormState in Fiber. (It does not include any
progressive enhancement features; those will be added later.)
useFormState is a hook for tracking state produced by async actions. It
has a signature similar to useReducer, but instead of a reducer, it
accepts an async action function.
```js
async function action(prevState, payload) {
// ..
}
const [state, dispatch] = useFormState(action, initialState)
```
Calling dispatch runs the async action and updates the state to the
returned value.
Async actions run before React's render cycle, so unlike reducers, they
can contain arbitrary side effects.
DiffTrain build for [456d153bb5](https://github.com/facebook/react/commit/456d153bb582798effa76c09bec2405ab2e392cf)
A transition that flows into a dehydrated boundary should not suspend if
the boundary is showing a fallback.
This is related to another issue where Fizz streams in the initial HTML
after a client navigation has already happened. That issue is not fixed
by this commit, but it does make it less likely. Need to think more
about the larger issue.
DiffTrain build for [ab31a9ed28](https://github.com/facebook/react/commit/ab31a9ed28d340172440e4b12e27d2af689249b3)
Import maps need to be emitted before any scripts or preloads so the
browser can properly locate these resources.
Unlike most scripts, importmaps are singletons meaning you can only have
one per document and they must appear before any modules are loaded or
preloaded. In the future there may be a way to dynamically add more
mappings however the proposed API for this seems likely to be a
javascript API and not an html tag.
Given the unique constraints here this PR implements React's support of
importMaps as the following
1. an `importMap` option accepting a plain object mapping module
specifier to path is accepted in any API that renders a preamble (head
content). Notably this precludes resume rendering because in resume
cases the preamble should have already been produced as part of the
prerender step.
2. the importMap is stringified and emitted as a `<script
type="importmap">...</script>` in the preamble.
3. the importMap is escaped identically to how bootstrapScriptContent is
escaped, notably, isntances of `</script>` are escaped to avoid breaking
out of the script context
Users can still render importmap tags however with Float enabled this is
rather pointless as most modules will be hoisted above the importmap
that is rendered. In practice this means the only functional way to use
import maps with React is to use this config API.
DiffTrain build for [9d4582dffd](https://github.com/facebook/react/commit/9d4582dffdea5b4dcb6a6093ea848d15423c7701)
This exposes, but does not yet implement, a new experimental API called
useFormState. It's gated behind the enableAsyncActions flag.
useFormState has a similar signature to useReducer, except instead of a
reducer it accepts an (async) action function. React will wait until the
promise resolves before updating the state:
```js
async function action(prevState, payload) {
// ..
}
const [state, dispatch] = useFormState(action, initialState)
```
When used in combination with Server Actions, it will also support
progressive enhancement — a form that is submitted before it has
hydrated will have its state transferred to the next page. However, like
the other action-related hooks, it works with fully client-driven
actions, too.
DiffTrain build for [b4cdd3e892](https://github.com/facebook/react/commit/b4cdd3e8922713f8c9817b004a0dc51be47bc5df)
This exposes a `resume()` API to go with the `prerender()` (only in
experimental). It doesn't work yet since we don't yet emit the postponed
state so not yet tested.
The main thing this does is rename ResponseState->RenderState and
Resources->ResumableState. We separated out resources into a separate
concept preemptively since it seemed like separate enough but probably
doesn't warrant being a separate concept. The result is that we have a
per RenderState in the Config which is really just temporary state and
things that must be flushed completely in the prerender. Most things
should be ResumableState.
Most options are specified in the `prerender()` and transferred into the
`resume()` but certain options that are unique per request can't be.
Notably `nonce` is special. This means that bootstrap scripts and
external runtime can't use `nonce` in this mode. They need to have a CSP
configured to deal with external scripts, but not inline.
We need to be able to restore state of things that we've already emitted
in the prerender. We could have separate snapshot/restore methods that
does this work when it happens but that means we have to explicitly do
that work. This design is trying to keep to the principle that we just
work with resumable data structures instead so that we're designing for
it with every feature. It also makes restoring faster since it's just
straight into the data structure.
This is not yet a serializable format. That can be done in a follow up.
We also need to vet that each step makes sense. Notably stylesToHoist is
a bit unclear how it'll work.
DiffTrain build for [31034b6de7](https://github.com/facebook/react/commit/31034b6de73c7cd9093e92a34e384d84c082aa4e)
renderToString is a legacy server API which used a trick to avoid having
the DOCTYPE included when rendering full documents by setting the root
formatcontext to HTML_MODE rather than ROOT_HTML_MODE. Previously this
was of little consequence but with Float the Root mode started to be
used for things like determining if we could flush hoistable elements
yet. In issue #27177 we see that hoisted elements can appear before the
<html> tag when using a legacy API `renderToString`.
This change exports a DOCTYPE from FizzConfigDOM and FizzConfigDOMLegacy
respectively, using an empty chunk in the legacy case. The only runtime
perf cost here is that for legacy APIs there is an extra empty chunk to
write when rendering a top level <html> tag which is trivial enough
Fixes#27177
DiffTrain build for [86198b9231](https://github.com/facebook/react/commit/86198b923199224b60533952b636348bb0484a6d)
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