Exposes (experimental) soft navigation heuristics to web developers, using both PerformanceObserver and the performance timeline.
Web developers have been asking for a way to take "soft navigations" - JS-driven navigations in Single Page Apps (SPA) - into account when exposing performance metrics. This exposes a browser heuristic to that effect. Doing that would enable developers to initially validate the heuristic compared to their own application- and framework-specific heuristics. Once validated, they can start relying on it when calculating the performance impact of various routes in their SPAs.
Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?
No milestones specified
Thanks for clarifying!Currently, the heuristic exposed doesn't (yet) expose FCP and LCP for those soft navigations. But let's assume that it does, and that is the eventual plan.Currently FCP includes any cross-origin paints in the same context, but doesn't provide any details about them other than the fact that they happened.So if we have a page where the only contentful element is a cross origin image, FCP would reveal when that image provided *any* data that enabled something to be painted.The same would be true for soft navigation FCP - after a user click and corresponding "navigation", the FCP fired would enable the page to get timing data on the initial decodable buffer of an image.I don't think that's worse than what FCP enables today.