Yeah, ugh, on this exact subject, Discourse (as @mitar alluded to) apparently implements its own version of "find in page" when you hit Ctrl+F, and it has a noticeable lag relative to Chrome's, a (pointless) "Search in this thread" checkbox (if I wanted to do anything else, why would I have hit Ctrl+F?), and it rejects search terms that are too short (wanted to find any mentions of the
vh unit in a CSS discussion? Too bad!)
I think this actually makes a decent point about what shouldn't be allowed in such an API, or at least what should be avoided (ie. it should probably be factored to only augment find-in-page search, in such a way that attempting to needlessly redefine in-page content searching feels extremely dirty).