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Issue 897650 link

Starred by 2 users
Status: WontFix
Owner:
npm@chromium.org
Closed: Oct 24
Cc:
maxlg@chromium.org
Components:
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: 1
Type: Bug



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First Input Event Timing data sometimes missing

Project Member Reported by tdres...@chromium.org, Oct 22 
Repro:
1. Dispatch a mouse move event which takes > 50ms.
2. Dispatch a click event.

I expect to see an event timing entry for the mousemove, and then a first event entry for the click.

The first event entry is missing.

Comment 1 by npm@chromium.org, Oct 22 

How are you detecting the first event entry? Currently we are only buffering first event entries that occur before onload (same behavior as other event entries) so my guess is that you're doing getEntriesByType? If you use a PerformanceObserver, does the first event show up?

Comment 2 by tdres...@chromium.org, Oct 23 

This is with a PO registered immediately.

I suspect that the code to prevent us from firing first-input multiple times is broken.

Comment 3 by npm@chromium.org, Oct 23

Labels: Needs-Feedback
Please provide a sample testcase. I tried the following and it works as expected:

<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Mousemove then click</title>
<body>
<p><a href="http://developer.mozilla.org/" id="mousy">Move your mouse here&hellip;</a></p>
<div id="bla" onclick="performance.now();">ClickME</div>
<script>
const observer = new PerformanceObserver(
  function(entryList) {
    entryList.getEntries().forEach(entry => {
      console.log(entry.entryType);
    });
  });
observer.observe({entryTypes: ['firstInput', 'event']});
document.getElementById("mousy").onmousemove = () => {
  let p = performance.now();
  while(performance.now() < p + 100) {}
}
</script>
</body>

Comment 4 by npm@chromium.org, Oct 24

Status: WontFix (was: Assigned)
Discussed with Tim in person, it seems this is working as intended. The explainer may need to be updated to allow not producing first input events when there are no event handlers.
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