The combo box is a dropdown with a typeahead behavior. This allows the user to either type a value or select a value from the list.
It needs a conclusive watermark which informs the user about the options to either start typing or to select an item from the dropdown. As the combobox is often used for a very long list of items (where it makes sense to allow typing in to refine the list), the watermark should also indicate what users can find in the dropdown list (e.g. favorites, often used, top items...).
Sizes and distances
Hover on combobox
Hover on item
The combobox can have additional features:
- Categories: Entries can be grouped in categories to organize the entries. The categories are separated with a line and a headline.
- Two-rowed entries: The additional information can help the user identify entries.
- Disabled entries: Sometimes entries are not available, in that case the entry is still shown, but it is disabled and therefore can't be selected. To give the user some information on why the entry is disabled, the reason is displayed in an overlay on hover (or tap on mobile).
On click the dropdown opens a list of several items for the user to choose from and the cursor is placed in the input field.
As soon as users start typing the list is refined. Once an item is selected, the dropdown closes and the input field is updated accordingly.
If there are a lot of items in the dropdown it often needs some time to load. The loading distractor indicates this action.