Comment by chrismorgan

Client-side routing for page-oriented stuff is certainly not a solved problem: the basics, sure, but not actually doing it properly. There are some parts of the experience that it’s not possible to do perfectly because the web doesn’t expose the necessary primitives, and exceptionally few things go beyond the basics of just clobbering and resetting scroll position on back/forward. To do it properly, you need to restore all transient UI state (form field contents/state, scroll positions, focus, selection, media playback position; zoom level, probably not implementable; and there may be more, though I don’t include things like <details open> as transient state since that’s put into the DOM) on back/forwards, and I don’t know if I’ve seen anything actually do that. Then there’s the matter of helping accessibility tech to realise a page change has occurred, and I’m not sure of the state of the art on that, but last time I looked (some years ago) I think it was bogged down in unreliable heuristic land rather than actually being solved.