Scenario: Users are performing data entry into an internal web application. At various points throughout the process, they need to specify things like:
- What person does this apply to?
- What vendor is this associated with?
Both of these fields would be extremely long lists, so they function as searchable dropdowns that search for matching results similar to this example. They key difference is that it is not reasonable to load and try to display the entire list of selections in a dropdown (easily 200+ items), so nothing (alternatively, a set of contextually relevant defaults) is displayed until a few characters have been entered to trigger the search.
Users already know what option they're looking for and it should always exist, so this is a case of "I want to quickly select the right option" moreso than "I'm not sure which option is best, let me figure out what sounds correct".
Question: One of these dropdowns may be optional, with an explicit "None" option. Should this None option always visible (making it add a small amount of noise to search results and probably an additional arrow-down required to select any of said results), or should it only be visible when no text is entered?
I can see justifications for both possibilities:
Only visible with no text: The enduser will already know whether or not they need to select the None option. If they do, they can choose it from the dropdown right then and there with no typing required; if they type something they're (presumably) looking for a particular result and thus wouldn't need to select the "None" option.
Always visible: Well, it's consistent. In some other use-cases (i.e. if it was "None of these" rather than "None") it makes more sense -- though I imagine in most of those cases the entire list should be visible in the first place.