UI Patterns
Combobox / Autocomplete
A text input with a popup list of options. One of the hardest ARIA patterns: role='combobox' + aria-expanded + aria-activedescendant + listbox. Broken implementations are everywhere — test with screen readers.
In plain terms
A type-ahead box that suggests options as you type — one of the hardest things to build accessibly, so test it carefully.
Why this matters
Type-ahead comboboxes are among the most-broken patterns on the web. When the roles and states are wrong, screen-reader users can't tell that suggestions appeared or which one is highlighted.
How to detect
Quick check
With a screen reader, type into the field: is the list announced, is the active option read as you arrow through it, and does selecting one update the input? Test in more than one screen reader.