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Enable the Layout Jank API in WPT agents and surface data in HARs
See original GitHub issueThe goal is to improve our telemetry of web pages’ layout stability. There’s an experimental API (in origin trial and behind a flag) that surfaces the % of the viewport that changes (aka “janks”) due to layout changes.
Per https://github.com/GoogleChrome/OriginTrials/issues/53#issuecomment-488367187 we can pass --enable-blink-features=LayoutInstabilityAPI on the command line to enable it.
Not sure what else we need to do to get the output in the HAR files. @pmeenan will it automatically appear in the BlinkFeatures object? We might also want to consider a custom metric to aggregate the data, as the output might be noisy.
- enable the API in WPT
- add a custom metric to WPT to calculate CLS
Issue Analytics
- State:
- Created 4 years ago
- Reactions:1
- Comments:9 (8 by maintainers)
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Yes there is a trace event called FrameLayoutJank.
https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/layout/jank_tracker.cc?q=TRACE_EVENT
Done. Try it out on WPT after an hour (so they can update) to make sure it is working as expected.