Add element and/or id fields to PerformanceEventTiming to indicate target of the event

[DanShappir]

I propose adding element and/or id fields to PerformanceEventTiming, similar to these fields in LargestContentfulPaint. These fields would indicate the target element of the event that was recorded. Having this information would be very beneficial:

1. It would make it much easier to identify user interactions that have long delays
2. In the context of "first-input", it would help determine which code should be loaded first/preload, based on common visitor interactions
3. Many sites would like to know which elements on the page visitors first interact with, regardless of performance

[npm1]

Thanks for the feedback! I agree that this would be useful, and this has been discussed in this issue #9. The main question I guess is whether to expose a single EventTarget or the list of all EventTargets (shadow DOM can cause this to be of length >0). Given shadow DOM encapsulation principles, I suspect that people would be opposed to the latter.

[DanShappir]

I'm in favor of a single EventTarget

[npm1]

Update: we have a concrete plan to add this, which will be a prerequisite for us shipping full Event Timing (for 'discrete' events) in Chrome.

[clelland]

Looks like this was shipped in Chrome as target; closing this.