feat: implement getServerSnapshot for useSyncExternalStore - #4979
Merged
Conversation
📊 Tachometer Benchmark ResultsSummary⏳ Benchmarks are currently running. Results below are out of date. duration
usedJSHeapSize
Results⏳ Benchmarks are currently running. Results below are out of date. create10kduration
usedJSHeapSize
filter-listduration
usedJSHeapSize
hydrate1kduration
usedJSHeapSize
many-updatesduration
usedJSHeapSize
replace1kduration
usedJSHeapSize
run-warmup-0
run-warmup-1
run-warmup-2
run-warmup-3
run-warmup-4
run-final
text-updateduration
usedJSHeapSize
tododuration
usedJSHeapSize
update10th1kduration
usedJSHeapSize
|
|
coverage: 98.339% (-0.2%) from 98.541% — ssssota:getServerSnapshot into preactjs:main |
ssssota
commented
Dec 20, 2025
ssssota
commented
Dec 20, 2025
ssssota
marked this pull request as ready for review
December 20, 2025 02:00
rschristian
reviewed
Dec 20, 2025
Co-Authored-By: rschristian <rschristian@users.noreply.github.com>
Co-Authored-By: rschristian <rschristian@users.noreply.github.com>
| getServerSnapshot | ||
| ) { | ||
| const value = | ||
| typeof window === 'undefined' || hydrating |
Member
There was a problem hiding this comment.
This or we use options._skipEffects
| typeof window === 'undefined' || hydrating | ||
| ? getServerSnapshot | ||
| ? getServerSnapshot() | ||
| : missingGetServerSnapshot() |
Member
There was a problem hiding this comment.
Let's not add oversized error strings, this seems a bit against our bundle philosophy
Member
There was a problem hiding this comment.
That (the oversized string) was my suggestion FWIW, my bad
| let oldBeforeRender = options._render; | ||
|
|
||
| /** @type {(vnode: import('./internal').VNode) => void} */ | ||
| options._render = _vnode => { |
Member
There was a problem hiding this comment.
If we move this to the render.js file you can benefit from options._render there and save more bytes
Member
There was a problem hiding this comment.
Having hooks.js only contain some hooks, not all, is kinda weird... what was the byte difference there, if you remember? Should we even keep this module around, or should it be inlined into render?
Member
There was a problem hiding this comment.
When I tried it locally it was 32b gzip
Member
There was a problem hiding this comment.
Roughly a third then, hefty.
JoviDeCroock
left a comment
JoviDeCroock
left a comment
Member
There was a problem hiding this comment.
The general trend of this looks good, left some comments on how to reduce bundle size. Let's get this into v11
Contributor
Author
|
@JoviDeCroock Thank you for the review! I've made the changes, so please take a look. |
Member
|
I meant move the whole hook over 😅 this made the byte size regress |
| ) { | ||
| const serverRendering = options._skipEffects || hydrationRoot; | ||
| if (serverRendering && !getServerSnapshot) { | ||
| throw new Error('Missing getServerSnapshot'); |
Member
There was a problem hiding this comment.
Remove the error all together imho, we can just fall back to regular snapshot.
Contributor
Author
There was a problem hiding this comment.
I will make that change as suggested!
Please note that React throws an error in this case.
If you omit this argument, rendering the component on the server will throw an error.
JoviDeCroock
approved these changes
Jul 31, 2026
JoviDeCroock
left a comment
JoviDeCroock
left a comment
Member
There was a problem hiding this comment.
Thank you for implementing this!
JoviDeCroock
added a commit
that referenced
this pull request
Jul 31, 2026
The getServerSnapshot test added in #4979 asserts React's effect ordering during hydration: the passive effect runs once for the server snapshot and once for the client snapshot. It got that ordering from the stale-effect flush in options._render that this branch removes. That flush is no longer how pending effects are drained -- the scheduler installed by preact/hooks flushes them before a scheduled render instead. `act` replaces options.debounceRendering, so it bypasses that scheduler and drains renders before effects. Run the test on the default scheduler, like the suspense and useSyncExternalStore bail-out tests on this branch already do; the assertions are unchanged and still match React.
Merged
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
close #4972