Intent to Extend Origin Trial: EventTiming
n...@chromium.org
Contact emails
n...@chromium.org, tdre...@chromium.org
Spec
Link to spec: https://wicg.github.io/event-timing/
Summary
Monitoring event latency today requires an event listener. This precludes measuring event latency early in page load, and adds unnecessary performance overhead. The Event Timing API gives developers insight into the latency of a subset of events triggered by user interaction. In order to capture user pain caused by slow initial interactions, the event timing API includes First Input Delay (FID).
Previous trial results are described at https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/mGkwLYpHOxM/T7pEAGVJCAAJ
Link to “Intent to Implement” blink-dev discussion
Goals for experimentation
We’d like feedback from a new customer which expressed interest in the OriginTrial. Previous Intent to Experiment:
https://groups.google.com/a/chromium.org/forum/#!searchin/blink-dev/Intent$20to$20Extend$20Origin$20Trial$3A$20EventTiming%7Csort:date/blink-dev/sJ4lxamz2V0/9aGztXjfDgAJ
Experimental timeline
Current experiment began in M68 and is set to end at the end of M72. We’d like to extend the experiment until the end of M74.
Any risks when the experiment finishes?
No - this is a performance analytics API.
Reason this experiment is being extended
There are two main reasons:
Allowing the new customer to try out the API, and potentially provide feedback.
We were planning to ship on M73 but were unable to do so due to https://bugs.chromium.org/p/chromium/issues/detail?id=914500. We have a plan to fix this bug so are hoping to ship soon but we depend on some Finch trial results so it’s unclear if we will make M74. We don’t want a long period of time during which this API is not available because it is exposed as an experimental metric in CrUX.
Ongoing technical constraints
None.
Debuggability
When enabled, FID is exposed via javascript either via PerformanceObserver (requires early registration) or via the performance timeline if it occurs before onload:
// Register observer during onload.
const performanceObserver = new PerformanceObserver …
performanceObserver.observe({entryTypes:['firstInput']});
// Or get it from the buffer.
performance.getEntriesByType(‘firstInput’);
Will this feature be supported on all five Blink platforms supported by Origin Trials (Windows, Mac, Linux, Chrome OS, and Android)?
Yes.
Link to entry on the feature dashboard
https://www.chromestatus.com/feature/5167290693713920
Philip Jägenstedt
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