web-platform-tests / web-platform-tests/interop
Layout Instability API (Core Web Vitals: Cumulative Layout Shift)
Nobody has claimed this yet.
- Dominant language
- JavaScript
- Stars
- 524
- Forks
- 35
- Avg merge
- 1d 4h
- Merged PRs (30d)
- 10
Description
Description
Visual stability is paramount to providing a good user experience.
Cumulative Layout Shift, the industry-standard measure of visual stability, is the final Core Web Vital that doesn't exist across all browsers. It's critically important our industry can measure visual stability across all browsers, given each engine has it's nuances.
This had strong positive feedback from developers last year but wasn't selected. In 2024, the Core Web Vitals were selected but CLS was excluded from the selection.
Specification
https://wicg.github.io/layout-instability/
web-feature
https://web-platform-dx.github.io/web-features-explorer/features/layout-instability/
Test Links
https://wpt.fyi/results/?q=feature:layout-instability
Additional Signals
- Firefox: Positive https://github.com/mozilla/standards-positions/issues/374
- WebKit: Unknown
Contributor guide
No contributing guide indexed for this repository
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the linked Layout Instability specification and review the web-features entry and WPT results for layout-instability. The issue does not identify files or a concrete change; first determine what Interop work is expected and what cross-browser test coverage would constitute completion.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- javascript
- Domain
- testing-qa, web-dev
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Active
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100