[reactive-element] Assume native constructible stylesheet support #5120

justinfagnani · 2025-10-13T17:39:47Z

DO NOT MERGE

Exploration of how much code we could remove if we assumed constructible stylesheet support, which is Baseline and available cross-browser since March 2023: https://developer.mozilla.org/en-US/docs/Web/API/CSSStyleSheet/CSSStyleSheet

This change saves 650 bytes.

changeset-bot · 2025-10-13T17:39:50Z

⚠️ No Changeset found

Latest commit: 4f6e612

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

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

github-actions · 2025-10-13T17:39:59Z

📊 Tachometer Benchmark Results

Summary

nop-update

this-change, tip-of-tree, previous-release: unsure 🔍 -6% - +9% (-0.74ms - +1.10ms)
^{this-change vs tip-of-tree}

render

this-change: 44.66ms - 58.05ms
this-change, tip-of-tree, previous-release: unsure 🔍 -5% - +5% (-0.92ms - +0.99ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -2% - +2% (-0.65ms - +0.74ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -6% - +57% (-1.45ms - +24.20ms)
^{this-change vs tip-of-tree}

update

this-change: 471.18ms - 478.40ms
this-change, tip-of-tree, previous-release: unsure 🔍 -4% - +5% (-1.67ms - +1.80ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -1% - +2% (-0.91ms - +1.55ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -3% - +1% (-12.71ms - +3.89ms)
^{this-change vs tip-of-tree}

update-reflect

this-change: 457.06ms - 461.63ms
this-change, tip-of-tree, previous-release: unsure 🔍 -2% - +1% (-9.62ms - +7.13ms)
^{this-change vs tip-of-tree}

Results

this-change

Browser: chrome-headless 140.0.0.0
Sample size: 50
Built by: Benchmarks #7005
Commit: 4f6e612

render

Version	Avg time	vs
	44.66ms - 58.05ms	-

update

Version	Avg time	vs
	471.18ms - 478.40ms	-

update-reflect

Version	Avg time	vs
	457.06ms - 461.63ms	-

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

Browser: chrome-headless 140.0.0.0
Sample size: 30
Built by: Benchmarks #7005
Commit: 4f6e612

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	19.39ms - 20.88ms	-	unsure 🔍 -5% - +5% -0.92ms - +0.99ms	unsure 🔍 -2% - +8% -0.36ms - +1.46ms
tip-of-tree tip-of-tree	19.50ms - 20.70ms	unsure 🔍 -5% - +5% -0.99ms - +0.92ms	-	unsure 🔍 -1% - +7% -0.28ms - +1.31ms
previous-release previous-release	19.06ms - 20.11ms	unsure 🔍 -7% - +2% -1.46ms - +0.36ms	unsure 🔍 -6% - +1% -1.31ms - +0.28ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	35.98ms - 38.40ms	-	unsure 🔍 -4% - +5% -1.67ms - +1.80ms	unsure 🔍 -5% - +3% -2.03ms - +1.16ms
tip-of-tree tip-of-tree	35.88ms - 38.36ms	unsure 🔍 -5% - +4% -1.80ms - +1.67ms	-	unsure 🔍 -6% - +3% -2.12ms - +1.11ms
previous-release previous-release	36.59ms - 38.66ms	unsure 🔍 -3% - +5% -1.16ms - +2.03ms	unsure 🔍 -3% - +6% -1.11ms - +2.12ms	-

nop-update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	12.29ms - 13.61ms	-	unsure 🔍 -6% - +9% -0.74ms - +1.10ms	unsure 🔍 -0% - +15% -0.01ms - +1.76ms
tip-of-tree tip-of-tree	12.13ms - 13.41ms	unsure 🔍 -8% - +6% -1.10ms - +0.74ms	-	unsure 🔍 -2% - +13% -0.17ms - +1.56ms
previous-release previous-release	11.49ms - 12.66ms	unsure 🔍 -13% - -0% -1.76ms - +0.01ms	unsure 🔍 -12% - +1% -1.56ms - +0.17ms	-

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

Browser: chrome-headless 140.0.0.0
Sample size: 50
Built by: Benchmarks #7005
Commit: 4f6e612

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	34.70ms - 35.71ms	-	unsure 🔍 -2% - +2% -0.65ms - +0.74ms	unsure 🔍 -3% - +1% -1.02ms - +0.39ms
tip-of-tree tip-of-tree	34.68ms - 35.64ms	unsure 🔍 -2% - +2% -0.74ms - +0.65ms	-	unsure 🔍 -3% - +1% -1.04ms - +0.33ms
previous-release previous-release	35.03ms - 36.00ms	unsure 🔍 -1% - +3% -0.39ms - +1.02ms	unsure 🔍 -1% - +3% -0.33ms - +1.04ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	71.64ms - 73.40ms	-	unsure 🔍 -1% - +2% -0.91ms - +1.55ms	unsure 🔍 -2% - +2% -1.35ms - +1.09ms
tip-of-tree tip-of-tree	71.35ms - 73.06ms	unsure 🔍 -2% - +1% -1.55ms - +0.91ms	-	unsure 🔍 -2% - +1% -1.65ms - +0.75ms
previous-release previous-release	71.81ms - 73.50ms	unsure 🔍 -2% - +2% -1.09ms - +1.35ms	unsure 🔍 -1% - +2% -0.75ms - +1.65ms	-

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

Browser: chrome-headless 140.0.0.0
Sample size: 50
Built by: Benchmarks #7005
Commit: 4f6e612

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	46.47ms - 66.02ms	-	unsure 🔍 -6% - +57% -1.45ms - +24.20ms	unsure 🔍 -19% - +36% -9.30ms - +17.92ms
tip-of-tree tip-of-tree	36.56ms - 53.17ms	unsure 🔍 -40% - +0% -24.20ms - +1.45ms	-	unsure 🔍 -36% - +9% -19.66ms - +5.53ms
previous-release previous-release	42.46ms - 61.40ms	unsure 🔍 -31% - +16% -17.92ms - +9.30ms	unsure 🔍 -14% - +46% -5.53ms - +19.66ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	482.75ms - 495.34ms	-	unsure 🔍 -3% - +1% -12.71ms - +3.89ms	unsure 🔍 -3% - +1% -13.13ms - +3.86ms
tip-of-tree tip-of-tree	488.05ms - 498.87ms	unsure 🔍 -1% - +3% -3.89ms - +12.71ms	-	unsure 🔍 -2% - +2% -8.09ms - +7.64ms
previous-release previous-release	487.98ms - 499.39ms	unsure 🔍 -1% - +3% -3.86ms - +13.13ms	unsure 🔍 -2% - +2% -7.64ms - +8.09ms	-

update-reflect

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	488.43ms - 499.40ms	-	unsure 🔍 -2% - +1% -9.62ms - +7.13ms	unsure 🔍 -2% - +1% -8.51ms - +7.09ms
tip-of-tree tip-of-tree	488.84ms - 501.49ms	unsure 🔍 -1% - +2% -7.13ms - +9.62ms	-	unsure 🔍 -2% - +2% -7.87ms - +8.94ms
previous-release previous-release	489.09ms - 500.17ms	unsure 🔍 -1% - +2% -7.09ms - +8.51ms	unsure 🔍 -2% - +2% -8.94ms - +7.87ms	-

_{tachometer-reporter-action v2 for Benchmarks}

github-actions · 2025-10-13T17:41:26Z

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

rictic · 2025-10-23T17:49:20Z

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


  // This is a getter so that it's lazy. In practice, this means stylesheets
  // are not created until the first element instance is made.
  get styleSheet(): CSSStyleSheet | undefined {


This can just be CSSStyleSheet, we can drop the | undefined here.

[reactive-element] Assume native constructible stylesheet support

4f6e612

rictic reviewed Oct 23, 2025

View reviewed changes

[reactive-element] Assume native constructible stylesheet support #5120

Are you sure you want to change the base?

[reactive-element] Assume native constructible stylesheet support #5120

Uh oh!

Conversation

justinfagnani commented Oct 13, 2025

Uh oh!

changeset-bot bot commented Oct 13, 2025

⚠️ No Changeset found

Uh oh!

github-actions bot commented Oct 13, 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 Oct 13, 2025

Uh oh!

rictic Oct 23, 2025

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

github-actions bot commented Oct 13, 2025 •

edited

Loading