Autocomplete input with listbox

How to test an autocomplete input with listbox

Gherkin Condensed WCAG

Given that I am on a page with an autocomplete input with listbox

1 Keyboard for mobile & desktop

WHEN I use the tab key to move focus to the text input I SEE focus is strongly visually indicated
Then when I use the arrow keys to select an option I SEE the selected option is the new text input value
Then when I use the enter key I SEE the selected option is changed and focus returns to the text input
Then when I use the escape key when the select is open I SEE it collapses and focus moves to the text input

2 Desktop screenreader

WHEN I use a desktop screenreader (NVDA, JAWS, VoiceOver) AND I use the tab key to move focus to the text input
- I HEAR Its purpose is clear
- I HEAR It identifies itself as a select, popup, menu/submenu, listbox or combobox
- I HEAR Its label is read and selected options are read
- I HEAR It indicates the value of the text input
Then when I use the arrow keys to select an option I HEAR the selected option is the new text input value
Then when I use the enter key I HEAR the selected option is changed and focus returns to the text input
Then when I use the escape key when the select is open I HEAR it collapses and focus moves to the text input

3 Mobile screenreader

WHEN I use a mobile screenreader (Talkback, VoiceOver) AND I swipe to focus on a select
- I HEAR Its purpose is clear
- I HEAR It identifies itself as a select, popup, menu/submenu, listbox or combobox
- I HEAR Its label is read and selected options are read
- I HEAR It indicates the value of the text input
Then when I doubletap with the select in focus I HEAR the selected option is changed

1 Keyboard & screen reader actions

When I use	I see/hear
Tab	Focus moves visibly to the text input
Arrow-keys	Focus moves to and selects the next option. If the textbox is empty and the listbox is not displayed, opens the listbox and moves visual focus to the next option. In both cases DOM focus remains on the textbox.
Enter	The textbox value is set to the content of the selected option. The listbox closes.
Escape	Clears the textbox. If the listbox is displayed, closes it.

2 Mobile screenreader gestures

When I use	I hear
Swipe	Focus moves to the input, traverses list
Double-tap	Opens select, chooses option

3 Screenreader output for all devices

Reads	I hear
Name	Its purpose is clear
Role	It identifies itself as a select, popup, menu/submenu, listbox or combobox
Group	Its label is read and selected options are read
State	It indicates the value of the text input

An autocomplete input with listbox must meet these WCAG principles.

1Perceivable

Is easy to identify as interactive
Text size is optically no smaller than 16px Helvetica
The text has a 4.5:1 minimum contrast ratio
Label is always visible (placeholder cannot be used as a label)
Color is not used as the only means of conveying information or state (error, success, focus, disabled etc)

2Operable

Is keyboard operable
The click/tap target area is no smaller than 44x44px
The disabled and focus states have a 3:1 minimum contrast ratio against default
The focus indication has a minimum area equal to the width of the element and 2px in height

3Understandable

The input purpose should be clear in the context of the whole page
The width of the input accommodates/affords the intended input, reinforcing its purpose

4Robust

Meets criteria across platforms, devices and viewports

Code examples

Custom listbox with autocomplete

Custom listboxes are notoriously difficult to build in an accessible fashion for screenreaders.

WAI-ARIA examples

Semantic input with datalist autocomplete

This simple example illustrates all the functionality of a listbox with inline autocomplete in Chrome and Firefox.
- This is not production ready code as its support across browsers is not uniform.
- A datalist is not fully supported in Safari, but is included in the newest Safari Technology Preview as of late 2022
- Support and functionality on mobile devices varies

<label for="favorite-nato-text">
  What's your favorite NATO letter?:
</label>
<input id="favorite-nato-text" 
       list="nato-letters" 
       type="text">
       
<datalist id="nato-letters"> 
  <option value="Alpha"> 
  <option value="Bravo"> 
  <option value="Charlie"> 
  <option value="Delta">
  <option value="Echo">
  <option value="Foxtrot">
  <option value="Golf">
  <option value="Hotel">
  <option value="India">
  <option value="Juliet">
  <option value="Kilo">
  <option value="Lima">
  <option value="Mike">
  <option value="November">
  <option value="Oscar">
  <option value="Papa">
  <option value="Quebec">
  <option value="Romeo">
  <option value="Sierra">
  <option value="Tango">
  <option value="Uniform">
  <option value="Victor">
  <option value="Whiskey">
  <option value="X-ray">
  <option value="Yankee">
  <option value="Zulu">
</datalist>

What's your favorite NATO letter?: