Prefix search in dropdown boxes is one of those small UX features that every self-respecting desktop UI kit has had since the antiquity, long before the term "U

Prefix search in dropdown boxes is one of those small UX features that every self-respecting desktop UI kit has had since the antiquity, long before the term "UX" was even a thing. It is also something that's missing in almost all naive web-based custom dropdown components. However, its discoverability is almost nonexistent, and it's rather awkward to use because you don't see what you're actually typing. How fast should I type before the builtin timeout erases the buffer? How do I know if I made a typo? Does backspace work? And so on. Blind typing and trying to second-guess the logic behind the feature is not very fun.