GoogleChrome / GoogleChrome/lighthouse

Timespan incorrectly captures CLS from user input

Open
#14,396 8 comments 0 reactions 0 assignees View on GitHub
bug P1.5 upstream-action-required
Dominant language
JavaScript
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Forks
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Avg merge
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Description

### FAQ

- [X] Yes, my issue is not about [variability](https://github.com/GoogleChrome/lighthouse/blob/master/docs/variability.md) or [throttling](https://github.com/GoogleChrome/lighthouse/blob/master/docs/throttling.md).
- [X] Yes, my issue is not about a specific accessibility audit (file with [axe-core](https://github.com/dequelabs/axe-core) instead).

### URL

https://web.dev/

### What happened?

When running lighthouse on timespan mode and resizing a page it shows high CLS.

### What did you expect?

it should be low as it is within the time window of a user-initiated layout shift, and the resizing is done by the user.

### What have you tried?

_No response_

### How were you running Lighthouse?

Chrome DevTools

### Lighthouse Version

9.6.2

### Chrome Version

105.0.0.0

### Node Version

_No response_

### OS

Mac

### Relevant log output

_No response_

Contributor guide

Open the contributing guide

Research direction

Reproduce the issue on https://web.dev/ using Lighthouse 9.6.2 in Chrome DevTools, with timespan mode and a user-driven resize. Then trace how the timespan run records CLS and compare the reported value with the expected treatment of user-initiated layout shifts; done means resizing no longer produces an incorrectly high CLS.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript
Domain
performance, tooling
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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