Re: [EXTERNAL] followup questions to the scroll presentation

We are experimenting with the EventTiming API as a way to evaluate user actions response times in Microsoft Office Online. By doing that we hope it will help us to rate a user session interactivity quality as well as focusing us on the user actions with slow response times so that we could detect regressions and try and improve performance for them. In addition, integrating this with custom instrumentations (or future js-self-profiler) we believe it will help us with root cause analysis for slow user actions and point us to the right place in the code which has most negative impact on the user.

Following the EventTiming API definition (https://wicg.github.io/event-timing/#performanceeventtiming) we are trying to use the event passed to the DOM event handler to correlate with the EventTimingEntry using event.type + event.timeStamp as a correlation key with entry.name + event.startTime. So far it seems to be a reasonable, but I'd be happy to hear if there are any thoughts about this approach.

We want to think about the performance entry "duration" attribute as the user action response time and assume actions with response times  > 100ms to be considered as negative user experience.

I hope this makes things clearer.

Thanks,

- Noam

________________________________
From: Benjamin De Kosnik <bdekoz@mozilla.com>
Sent: Thursday, May 27, 2021 10:18 PM
To: Noam Helfman <noamh@microsoft.com>; public-web-perf <public-web-perf@w3.org>
Subject: [EXTERNAL] followup questions to the scroll presentation

Thanks for the presentation today Nicolás/Hongbo. Very interesting.

I have some follow-up questions for Noam: does Microsoft implement their own event id for their use of perf event timing, or how are they working around the existing limitations right now? More detail on how/what they are doing this now would be appreciated. It was a bit unclear yet tantalizing what is being attempted here...

Sean and I spent some time after the meeting going over cases for event id and grouping. First, would the event id be the same as the interaction id?

For disambiguating scroll events, here are some possible scenarios we want clarified, would these be grouped with an event id?

1. scroll plus alt keys, shift keys (keydown)
2. scroll plus scroll wheel press as mouse down event
3. dragstart above the fold, move below the fold (is this a scroll or nav event?), release dragend

best,
Benjamin