What guidelines exist when working with autocomplete widgets? I'm hoping for general guidelines that apply across different application types: web, desktop, and mobile.
- Never update the search input with one of the results unless the user requests it.
- Provide keyboard and mouse access for selecting results.
- Look-behind is a nice complement to look-ahead.
I've observed a few other practices:
- Highlighting the searched-for term
- Returning the count of matching items
- Providing an action indicator upon selection (but not activation) of an autocomplete entry
- Offering the originally typed text in the autocompletion list
In addition, the following questions may be asked when providing suggestions:
- How many hints/suggestions should be provided?
- How do you resolve those that should be displayed when many are available?
- Should suggestions take into account likely spelling or typing errors?
Any responses discussing more complicated syntaxes like boolean expressions would also be helpful.