[reactive-element] fixes inconsistent initial values in changed properties by sorvell · Pull Request #4949 · lit/lit

sorvell · 2025-03-21T14:19:59Z

changeset-bot · 2025-03-21T14:20:03Z

🦋 Changeset detected

Latest commit: ecb081a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@lit/reactive-element	Patch
lit	Patch
lit-element	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

github-actions · 2025-03-21T14:20:15Z

📊 Tachometer Benchmark Results

Summary

nop-update

this-change, tip-of-tree, previous-release: unsure 🔍 -7% - +11% (-0.88ms - +1.34ms)
^{this-change vs tip-of-tree}

render

this-change: 43.36ms - 52.18ms
this-change, tip-of-tree, previous-release: unsure 🔍 -7% - +0% (-1.35ms - +0.03ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -3% - +1% (-0.97ms - +0.41ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -2% - +65% (+1.01ms - +30.64ms)
^{this-change vs tip-of-tree}

update

this-change: 478.10ms - 482.00ms
this-change, tip-of-tree, previous-release: unsure 🔍 -6% - +1% (-2.46ms - +0.47ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -2% - +2% (-1.37ms - +1.16ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: faster ✔ 0% - 2% (0.79ms - 11.98ms)
^{this-change vs tip-of-tree}

update-reflect

this-change: 472.85ms - 477.01ms
this-change, tip-of-tree, previous-release: unsure 🔍 -1% - +2% (-3.94ms - +9.96ms)
^{this-change vs tip-of-tree}

Results

this-change

Browser: chrome-headless 134.0.0.0
Sample size: 50
Built by: Benchmarks #6709
Commit: ecb081a

render

Version	Avg time	vs
	43.36ms - 52.18ms	-

update

Version	Avg time	vs
	478.10ms - 482.00ms	-

update-reflect

Version	Avg time	vs
	472.85ms - 477.01ms	-

this-change, tip-of-tree, previous-release

Browser: chrome-headless 134.0.0.0
Sample size: 30
Built by: Benchmarks #6709
Commit: ecb081a

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	18.63ms - 19.37ms	-	unsure 🔍 -7% - +0% -1.35ms - +0.03ms	unsure 🔍 -4% - +1% -0.85ms - +0.24ms
tip-of-tree tip-of-tree	19.07ms - 20.23ms	unsure 🔍 -0% - +7% -0.03ms - +1.35ms	-	unsure 🔍 -2% - +5% -0.35ms - +1.05ms
previous-release previous-release	18.91ms - 19.70ms	unsure 🔍 -1% - +4% -0.24ms - +0.85ms	unsure 🔍 -5% - +2% -1.05ms - +0.35ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	36.06ms - 38.35ms	-	unsure 🔍 -6% - +1% -2.46ms - +0.47ms	unsure 🔍 -7% - +1% -2.54ms - +0.37ms
tip-of-tree tip-of-tree	37.29ms - 39.11ms	unsure 🔍 -1% - +7% -0.47ms - +2.46ms	-	unsure 🔍 -4% - +3% -1.37ms - +1.20ms
previous-release previous-release	37.38ms - 39.19ms	unsure 🔍 -1% - +7% -0.37ms - +2.54ms	unsure 🔍 -3% - +4% -1.20ms - +1.37ms	-

nop-update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	11.62ms - 13.15ms	-	unsure 🔍 -7% - +11% -0.88ms - +1.34ms	unsure 🔍 -14% - +2% -1.87ms - +0.34ms
tip-of-tree tip-of-tree	11.35ms - 12.96ms	unsure 🔍 -11% - +7% -1.34ms - +0.88ms	-	unsure 🔍 -16% - +1% -2.13ms - +0.14ms
previous-release previous-release	12.35ms - 13.94ms	unsure 🔍 -3% - +15% -0.34ms - +1.87ms	unsure 🔍 -2% - +18% -0.14ms - +2.13ms	-

this-change, tip-of-tree, previous-release

Browser: chrome-headless 134.0.0.0
Sample size: 50
Built by: Benchmarks #6709
Commit: ecb081a

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	35.33ms - 36.01ms	-	unsure 🔍 -3% - +1% -0.97ms - +0.41ms	unsure 🔍 -1% - +1% -0.40ms - +0.47ms
tip-of-tree tip-of-tree	35.35ms - 36.55ms	unsure 🔍 -1% - +3% -0.41ms - +0.97ms	-	unsure 🔍 -1% - +3% -0.34ms - +0.98ms
previous-release previous-release	35.36ms - 35.91ms	unsure 🔍 -1% - +1% -0.47ms - +0.40ms	unsure 🔍 -3% - +1% -0.98ms - +0.34ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	67.79ms - 69.72ms	-	unsure 🔍 -2% - +2% -1.37ms - +1.16ms	unsure 🔍 -1% - +2% -0.63ms - +1.58ms
tip-of-tree tip-of-tree	68.03ms - 69.67ms	unsure 🔍 -2% - +2% -1.16ms - +1.37ms	-	unsure 🔍 -1% - +2% -0.41ms - +1.56ms
previous-release previous-release	67.74ms - 68.82ms	unsure 🔍 -2% - +1% -1.58ms - +0.63ms	unsure 🔍 -2% - +1% -1.56ms - +0.41ms	-

this-change, tip-of-tree, previous-release

Browser: chrome-headless 134.0.0.0
Sample size: 50
Built by: Benchmarks #6709
Commit: ecb081a

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	54.30ms - 77.28ms	-	unsure 🔍 -2% - +65% +1.01ms - +30.64ms	unsure 🔍 -16% - +40% -8.85ms - +22.54ms
tip-of-tree tip-of-tree	40.60ms - 59.32ms	faster ✔ 5% - 44% 1.01ms - 30.64ms	-	unsure 🔍 -37% - +7% -23.20ms - +5.23ms
previous-release previous-release	48.25ms - 69.65ms	unsure 🔍 -33% - +12% -22.54ms - +8.85ms	unsure 🔍 -13% - +49% -5.23ms - +23.20ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	478.12ms - 486.18ms	-	faster ✔ 0% - 2% 0.79ms - 11.98ms	unsure 🔍 -2% - +1% -7.97ms - +4.27ms
tip-of-tree tip-of-tree	484.65ms - 492.42ms	slower ❌ 0% - 2% 0.79ms - 11.98ms	-	unsure 🔍 -0% - +2% -1.49ms - +10.56ms
previous-release previous-release	479.39ms - 488.60ms	unsure 🔍 -1% - +2% -4.27ms - +7.97ms	unsure 🔍 -2% - +0% -10.56ms - +1.49ms	-

update-reflect

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	495.16ms - 503.01ms	-	unsure 🔍 -1% - +2% -3.94ms - +9.96ms	unsure 🔍 -1% - +2% -2.97ms - +7.67ms
tip-of-tree tip-of-tree	490.34ms - 501.81ms	unsure 🔍 -2% - +1% -9.96ms - +3.94ms	-	unsure 🔍 -1% - +1% -7.43ms - +6.10ms
previous-release previous-release	493.15ms - 500.33ms	unsure 🔍 -2% - +1% -7.67ms - +2.97ms	unsure 🔍 -1% - +1% -6.10ms - +7.43ms	-

_{tachometer-reporter-action v2 for Benchmarks}

github-actions · 2025-03-21T14:22:02Z

The size of lit-html.js and lit-core.min.js are as expected.

sorvell · 2025-03-24T10:51:59Z

@freshp86 can you help verify that this version would address the issues you're seeing? Thanks.

freshp86 · 2025-03-24T19:48:33Z

@freshp86 can you help verify that this version would address the issues you're seeing? Thanks.

Will give it a shot and report back, but unfortunately trying non-released versions of Lit within local Chromium builds is not very straight forward.

freshp86 · 2025-03-25T23:07:09Z

@freshp86 can you help verify that this version would address the issues you're seeing? Thanks.

Will give it a shot and report back, but unfortunately trying non-released versions of Lit within local Chromium builds is not very straight forward.

I have checked out Lit, patched this PR, and successfully ran npm run build locally. Having said that, in order to try this change in the context of Chromium I need to recreate the files that are distributed by npm install lit and I can't find them. If you can help me recreate those files locally, then I can try verifying whether these fixes are sufficient for our case. Thanks!

sorvell · 2025-03-26T13:45:14Z

If you can help me recreate those files locally

For quick testing, maybe you can just copy the ReactiveElement and LitElement out and make your base class extend from those?

freshp86 · 2025-03-26T23:29:37Z

For quick testing, maybe you can just copy the ReactiveElement and LitElement out and make your base class extend from those?

Thanks! I have partially verified that these would work for us. For the record here is how I went about it.

Checked out Lit locally, patched this PR, and succesfully ran npm run build
Copied the generated packages/reactive-element/reactive-element.js file to Chromium's third_party/node/node_modules/@lit/reactive-element/reactive-element.js.
Copied the generated packages/lit-element/lit-element.js file to Chromium's third_party/node/node_modules/lit-element/lit-element.js .
Note that we still use "lit": "3.0.2" in our package.json, so the files above have been copied on top of that version.
Reverted the workarounds we added at https://chromium-review.googlesource.com/c/chromium/src/+/6349561 and https://chromium-review.googlesource.com/c/chromium/src/+/6373768 (did not revert the updated tests for CrLitElement class)
Re-built our tests and ran all CrLitElement tests which passed.

I am not able to actually spawn our trybots with the modified Lit in Chromium's third_party/, to run all of the tests with these changes, so there is still a chance something might have been missed if not covered by the CrLitElement unit tests, but the fact that CrLitElement tests are passing with the workarounds reverted seems very promising.

packages/reactive-element/src/reactive-element.ts

Co-authored-by: Justin Fagnani <justinfagnani@google.com>

Fixes #4916

159ff4d

sorvell requested a review from justinfagnani March 21, 2025 14:19

sorvell requested a review from kevinpschaaf as a code owner March 21, 2025 14:20

justinfagnani approved these changes Mar 28, 2025

View reviewed changes

packages/reactive-element/src/reactive-element.ts Outdated Show resolved Hide resolved

sorvell and others added 3 commits April 1, 2025 07:20

Update packages/reactive-element/src/reactive-element.ts

97b6e6f

Co-authored-by: Justin Fagnani <justinfagnani@google.com>

Merge branch 'main' into changed-properties-initial

69d6228

update size

ecb081a

sorvell merged commit 3e2f87f into main Apr 2, 2025
9 checks passed

sorvell deleted the changed-properties-initial branch April 2, 2025 16:43

lit-robot mentioned this pull request Apr 10, 2025

Version Packages #4969

Merged

Conversation

sorvell commented Mar 21, 2025

Uh oh!

changeset-bot bot commented Mar 21, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

🦋 Changeset detected

Uh oh!

github-actions bot commented Mar 21, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

📊 Tachometer Benchmark Results

Summary

nop-update

render

update

update-reflect

Results

render

update

update-reflect

render

update

nop-update

render

update

render

update

update-reflect

Uh oh!

github-actions bot commented Mar 21, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

sorvell commented Mar 24, 2025

Uh oh!

freshp86 commented Mar 24, 2025

Uh oh!

freshp86 commented Mar 25, 2025

Uh oh!

sorvell commented Mar 26, 2025

Uh oh!

freshp86 commented Mar 26, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

changeset-bot bot commented Mar 21, 2025 •

edited

Loading

github-actions bot commented Mar 21, 2025 •

edited

Loading

github-actions bot commented Mar 21, 2025 •

edited

Loading

freshp86 commented Mar 26, 2025 •

edited

Loading