Fire Paint Timing events for soft navigations #168
Description
Hi,
There doesn't seem to be a clean method to 'reset / rerun' observers. This becomes relevant for SPA style sites. The PerformanceObserver sees just the one page, so when a user browsing the site goes to a new route, the figures from the observer are either for the initial route, or worse a combination of all the routes visited, rather than the route being browsed.
This is especially noticeable on something like CLS:
User lands on example.com/foo
The observers are initialised and data collected
User clicks to example.com/foo/bar
The observers are still running from example.com/foo, and also the new 'page' example.com/foo/bar
Something Cumulative Layout Shift would routes /foo & /foo/bar combined, leading to potentially wildy wrong metrics.
Some method to fire a re-initialization, or for this to happen on URL changing would make collection of these metrics much better on SPA sites, there's a huge amount of JavaScript SPAs, and SSR/Hydration frameworks like next.js, nuxt, sapper etc. this could benefit.