useId #22644
Merged
useId #22644
Conversation
This file contains 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
facebook-github-bot
added
CLA Signed
React Core Team
|
Comparing: a0d991f...371302f Critical size changesIncludes critical production bundles, as well as any change greater than 2%:
Significant size changesIncludes any change greater than 0.2%: Expand to show
|
acdlite
force-pushed
the
useid
branch
6 times, most recently
from
75a0cc2
to
78df833
Compare
crypt096
approved these changes
Oct 30, 2021
acdlite
force-pushed
the
useid
branch
2 times, most recently
from
0e5c259
to
3fbc388
Compare
eps1lon
reviewed
Oct 31, 2021
Comment on lines
+286
to
+291
| const divs = container.querySelectorAll('div'); | ||
|
|
||
| // Confirm that every id matches the expected pattern | ||
| for (let i = 0; i < divs.length; i++) { | ||
| // Example: R:clalalalalalalala... | ||
| expect(divs[i].id).toMatch(/^R:.(((al)*a?)((la)*l?))*$/); |
There was a problem hiding this comment.
For small trees collision is implicitly tested with a snapshot. But testing for collision is probably more interesting for large trees anyway. Does this make sense?
Suggested change
| const divs = container.querySelectorAll('div'); | |
| // Confirm that every id matches the expected pattern | |
| for (let i = 0; i < divs.length; i++) { | |
| // Example: R:clalalalalalalala... | |
| expect(divs[i].id).toMatch(/^R:.(((al)*a?)((la)*l?))*$/); | |
| const divs = container.querySelectorAll('div'); | |
| const ids = new Set(); | |
| // Confirm that every id matches the expected pattern and is unique | |
| for (let i = 0; i < divs.length; i++) { | |
| // Example: R:clalalalalalalala... | |
| expect(divs[i].id).toMatch(/^R:.(((al)*a?)((la)*l?))*$/); | |
| expect(ids).not.toContain(divs[i].id); | |
| ids.add(divs[i].id); |
There was a problem hiding this comment.
In this particular test it’s probably not that interesting because the structure of the tree follows such a rigid pattern. I’m planning to do this with a fuzz tester like we do for other features like context and Suspense.
gaearon
reviewed
Oct 31, 2021
| @@ -656,6 +656,33 @@ describe('ReactHooksInspectionIntegration', () => { | |||
| }); | |||
| }); | |||
|
|
|||
| it('should support useOpaqueIdentifier hook', () => { | |||
gaearon
reviewed
Oct 31, 2021
| // <B /> | ||
| // </> | ||
| // | ||
| // However, we cannot skip any materializes an id. Otherwise, a parent id that |
diegohaz
reviewed
Nov 1, 2021
| it('should support useId hook', () => { | ||
| function Foo(props) { | ||
| const id = React.unstable_useId(); | ||
| const [state] = React.useState(() => 'hello', []); |
There was a problem hiding this comment.
Does React.useState support a second argument? What does this stand for?
There was a problem hiding this comment.
No this was just copy pasta haha
Ids are base 32 strings whose binary representation corresponds to the
position of a node in a tree.
Every time the tree forks into multiple children, we add additional bits
to the left of the sequence that represent the position of the child
within the current level of children.
00101 00010001011010101
╰─┬─╯ ╰───────┬───────╯
Fork 5 of 20 Parent id
The leading 0s are important. In the above example, you only need 3 bits
to represent slot 5. However, you need 5 bits to represent all the forks
at the current level, so we must account for the empty bits at the end.
For this same reason, slots are 1-indexed instead of 0-indexed.
Otherwise, the zeroth id at a level would be indistinguishable from
its parent.
If a node has only one child, and does not materialize an id (i.e. does
not contain a useId hook), then we don't need to allocate any space in
the sequence. It's treated as a transparent indirection. For example,
these two trees produce the same ids:
<> <>
<Indirection> <A />
<A /> <B />
</Indirection> </>
<B />
</>
However, we cannot skip any materializes an id. Otherwise, a parent id
that does not fork would be indistinguishable from its child id. For
example, this tree does not fork, but the parent and child must have
different ids.
<Parent>
<Child />
</Parent>
To handle this scenario, every time we materialize an id, we allocate a
new level with a single slot. You can think of this as a fork with only
one prong, or an array of children with length 1.
It's possible for the the size of the sequence to exceed 32 bits, the
max size for bitwise operations. When this happens, we make more room by
converting the right part of the id to a string and storing it in an
overflow variable. We use a base 32 string representation, because 32 is
the largest power of 2 that is supported by toString(). We want the base
to be large so that the resulting ids are compact, and we want the base
to be a power of 2 because every log2(base) bits corresponds to a single
character, i.e. every log2(32) = 5 bits. That means we can lop bits off
the end 5 at a time without affecting the final result.
Stores the tree context on the dehydrated Suspense boundary's state object so it resume where it left off.
salazarm
approved these changes
Nov 1, 2021
| 'B', | ||
| ]); | ||
| // The insertions should not cause a mismatch. | ||
| expect(container).toMatchInlineSnapshot(` |
There was a problem hiding this comment.
Should we also test deletions? I'm guessing we won't match if a divWithID is missing on the client? Maybe we should encode it in the html?
There was a problem hiding this comment.
Yeah I can add a test for deleting a sibling. Or do you mean deleting the Suspense boundary before it hydrates?
There was a problem hiding this comment.
Discussed out-of-band, added more tests
Demonstrates that selective hydration works and ids are preserved even after subsequent client updates.
This was referenced Nov 8, 2024
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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.
Partial renderer (legacy server renderer) support? Do we need this?[I think I'll punt on this for now, since in open source the legacy API is implemented on top of the new renderer.]New hook API that generates stable ids during server rendering and hydration to avoid mismatches.
Outside of server-rendered content, it falls back to a global counter.
This is intended to replace
useOpaqueIdentifier.Id generation algorithm
Ids are base 32 strings whose binary representation corresponds to the position of a node in a tree.
Every time the tree forks into multiple children, we add additional bits to the left of the sequence that represent the position of the child within the current level of children.
The leading 0s are important. In the above example, you only need 3 bits to represent slot 5. However, you need 5 bits to represent all the forks at the current level, so we must account for the empty bits at the end.
For this same reason, slots are 1-indexed instead of 0-indexed. Otherwise, the zeroth id at a level would be indistinguishable from its parent.
If a node has only one child, and does not materialize an id (i.e. does not contain a useId hook), then we don't need to allocate any space in the sequence. It's treated as a transparent indirection. For example, these two trees produce the same ids:
However, we cannot skip any node that materializes an id. Otherwise, a parent id that does not fork would be indistinguishable from its child id. For example, this tree does not fork, but the parent and child must have different ids.
To handle this scenario, every time we materialize an id, we allocate a new level with a single slot. You can think of this as a fork with only one prong, or an array of children with length 1.
It's possible for the the size of the sequence to exceed 32 bits, the max size for bitwise operations. When this happens, we make more room by converting the right part of the id to a string and storing it in an overflow variable. We use a base 32 string representation, because 32 is the largest power of 2 that is supported by toString(). We want the base to be large so that the resulting ids are compact, and we want the base to be a power of 2 because every log2(base) bits corresponds to a single character, i.e. every log2(32) = 5 bits = 1 base 32 character. That means we can lop bits off the end 5 at a time without affecting the final result.