Facebook currently relies on being able to hydrate hidden HTML. So
skipping those trees is a regression.
We don't have a proper solution for this in the new API yet. So I'm
reverting it to match the old behavior.
Now the server renderer will treat LegacyHidden the same as a fragment,
with no other special behavior. We can only get away with this because
we assume that every instance of LegacyHidden is accompanied by a host
component wrapper. In the hidden mode, the host component is given a
`hidden` attribute, which ensures that the initial HTML is not visible.
To support the use of LegacyHidden as a true fragment, without an extra
DOM node, we will have to hide the initial HTML in some other way.
* Warn if MutableSource snapshot is a function
useMutableSource does not properly support snapshots that are functions. In part this is because of how it is implemented internally (the function gets mistaken for a state updater function). To fix this we could just wrap another function around the returned snapshot, but this pattern seems problematic to begin with- because the function that gets returned might itself close over mutable values, which would defeat the purpose of using the hook in the first place.
This PR proposes adding a new DEV warning if the snapshot returned is a function. It does not change the behavior (meaning that a function could still work in some cases- but at least the current behavior prevents passing around a closure that may later become stale unless you're really intentional about it e.g. () => () => {...}).
* Replaced .warn with .error
* useMutableSource hydration support
* Remove unnecessary ReactMutableSource fork
* Replaced root.registerMutableSourceForHydration() with mutableSources option
* Response to PR feedback:
1. Moved mutableSources root option to hydrationOptions object
2. Only initialize root mutableSourceEagerHydrationData if supportsHydration config is true
3. Lazily initialize mutableSourceEagerHydrationData on root object
This is a bit gross but I need to be able to access it without importing
the renderer.
There might be a better way but I need this to unblock internal bugfix.
Deferring a hidden tree is only supported in Concurrent Mode.
The missing check leads to an infinite loop when an update is scheduled
inside a hidden tree, because the pending work never gets reset.
This "accidentally" worked in the old reconciler because the heurstic
we used to detect offscreen trees was if `childExpirationTime`
was `Never`.
In the new reconciler, we check the tag instead. Which means we also
need to check the mode, like we do in the begin phase.
We should move this check out of the hot path. It shouldn't have been
in the hot path of the old reconciler, either.
Probably by moving `resetChildLanes` into the switch statement
in ReactFiberCompleteWork.
Need this to unblock www. Not sure yet how we'll support this properly
long term.
While adding this, I noticed that the normal "hidden" mode of
LegacyHidden doesn't work properly because it doesn't toggle the
visibility of newly inserted nodes. This is fine for now since we only
use it via a userspace abstraction that wraps the children in an
additional node. But implementing this correctly is required for us
to start using it like a fragment, without the wrapper node.
This package is missing the license attribute (or a license file).
Being a sub-package of React, it should get the same license, however, none was specified.
A scan with `license_checker` would recognize this as `UNKNOWN`.
* skip reading element for imported data
* rename nodes & enable store lookup for components tab
* replace names
* Added some more test coverage; reverted rename
Co-authored-by: Brian Vaughn <bvaughn@fb.com>
The function you provide will only be passed a child and an index. It will not be passed a key. This is confirmed in the source, the Flow types, and the jsdoc comments.
* Add LegacyHidden to server renderer
When the tree is hidden, the server renderer renders nothing. The
contents will be completely client rendered.
When the tree is visible it acts like a fragment.
The future streaming server renderer may want to pre-render these trees
and send them down in chunks, as with Suspense boundaries.
* Force client render, even at Offscreen pri
The motivation for doing this is to make it impossible for additional
uses of pre-rendering to sneak into www without going through the
LegacyHidden abstraction. Since this feature was already disabled in
the new fork, this brings the two closer to parity.
The LegacyHidden abstraction itself still needs to opt into
pre-rendering somehow, so rather than totally disabling the feature, I
updated the `hidden` prop check to be obnoxiously specific. Before, you
could set it to any truthy value; now, you must set it to the string
"unstable-do-not-use-legacy-hidden".
The node will still be hidden in the DOM, since any truthy value will
cause the browser to apply a style of `display: none`.
I will have to update the LegacyHidden component in www to use the
obnoxious string prop. This doesn't block merge, though, since the
behavior is gated by a dynamic flag. I will update the component before
I enable the flag.
* Failing useMutableSource test
If a source is mutated after initial read but before subscription is set
up, it should still entangle all pending mutations even if snapshot of
new subscription happens to match.
Test case illustrates how not doing this can lead to tearing.
* Fix useMutableSource tearing bug
Fix is to move the entanglement call outside of the block that checks
if the snapshot has changed.
* useMutableSource: "Entangle" instead of expiring
A lane is said to be entangled with another when it's not allowed to
render in a batch that does not also include the other lane.
This commit implements entanglement for `useMutableSource`. If a source
is mutated in between when it's read in the render phase, but before
it's subscribed to in the commit phase, we must account for whether the
same source has pending mutations elsewhere. The old subscriptions must
not be allowed to re-render without also including the new subscription
(and vice versa), to prevent tearing.
In the old reconciler, we did this by synchronously flushing all the
pending subscription updates. This works, but isn't ideal. The new
reconciler can entangle the updates without de-opting to sync.
In the future, we plan to use this same mechanism for other features,
like skipping over intermediate useTransition states.
* Use clz instead of ctrz to pick an arbitrary lane
Should be slightly faster since most engines have built-in support.
* [eslint-plugin-react-hooks] reproduce bug with a test and fix it (#18902)
Since we only reserve `-Effect` suffix, react-hooks/exhaustive-deps is
expected to succeed without warning on a custom hook which contains -Effect- in
the middle of it's name (but does NOT contain it as a suffix).
* [eslint-plugin-react-hooks] reproduced bug with a test and fix it
Since we only reserve `-Effect` suffix, react-hooks/exhaustive-deps is expected
to succeed without warning on a render helper which contains -use- in the middle
of it's name (but does NOT contain it as a prefix, since that would violate hook
naming convetion).
Co-authored-by: Boris Sergeyev <boris.sergeyev@quolab.com>
Julien DeniauandDan Abramov
Yann アウネ Eves
Brian Vaughn
Dan Abramov
Andrew Clark
yjimkandJimmy Cann
Dominic Gannaway
Sebastian Markbåge
Toru Kobayashi
Sebastian SilbermannandBrian Vaughn
Gabriele Prestifilippo
Ricky Vetter
Sophie Alpert
Boris SergeevandBoris Sergeyev