SuperOleg39

Hi! Try to fix this, have a little problem, if i want to add `config.node(false)` shortcut, because need a save backward compatibility, and can't make `config.node` callable and ChainedMap instance...

@edmorley Hello! If you have a time, need PR review)

> beforeUnload is probably too early (which explains why the timeout helps there). The web-vitals code uses a combination of pagehide and visibilitychange (whichever comes first) to detect backgrounding or...

As I understand right, and with `visibilitychange` application event handler can be fired before `web-vitals` event handler, and we will have the same problem

> You should be reporting data when the callback is invoked, not separately from when the callback is invoked. Our approach is close to this reciepe with batching - https://github.com/GoogleChrome/web-vitals#batch-multiple-reports-together,...

> That approach will work fine with reportAllChanges. That's the approach I use on my website as well. Thanks a lot for the answer, and of course for the great...

> That approach will work fine with reportAllChanges. That's the approach I use on my website as well. Maybe found a one problem - with `reportAllChanges `, sometimes `onCLS` callback...

> I don't think the behavior here is different between when reportAllChanges is true vs. when it's false, but let me know if it is (ideally with steps to repo)....

For me it is wrong, because no chance to measure CLS, if CLS called before FCP for some reasons

Found, it was because I also add `reportAllChanges: true` to `onFCP` callback, so maybe it is expected behaviour