add aria-orientation to the Listbox component

By default the `Listbox` will have an orientation of `vertical`. When
you pass the `horizontal` prop to the `Listbox` component then the
`aria-orientation` will be set to `horizontal`.

Additionally, we swap the previous/next keys:

- Vertical: ArrowUp/ArrowDown
- Horizontal: ArrowLeft/ArrowRight

packages/@headlessui-react/src/components/listbox/listbox.tsx

@@ -46,10 +46,14 @@ type ListboxOptionDataRef = MutableRefObject<{
 
 interface StateDefinition {
   listboxState: ListboxStates
+
+  orientation: 'horizontal' | 'vertical'
+
   propsRef: MutableRefObject<{ value: unknown; onChange(value: unknown): void }>
   labelRef: MutableRefObject<HTMLLabelElement | null>
   buttonRef: MutableRefObject<HTMLButtonElement | null>
   optionsRef: MutableRefObject<HTMLUListElement | null>
+
   disabled: boolean
   options: { id: string; dataRef: ListboxOptionDataRef }[]
   searchQuery: string
@@ -61,6 +65,7 @@ enum ActionTypes {
   CloseListbox,
 
   SetDisabled,
+  SetOrientation,
 
   GoToOption,
   Search,
@@ -74,6 +79,7 @@ type Actions =
   | { type: ActionTypes.CloseListbox }
   | { type: ActionTypes.OpenListbox }
   | { type: ActionTypes.SetDisabled; disabled: boolean }
+  | { type: ActionTypes.SetOrientation; orientation: StateDefinition['orientation'] }
   | { type: ActionTypes.GoToOption; focus: Focus.Specific; id: string }
   | { type: ActionTypes.GoToOption; focus: Exclude<Focus, Focus.Specific> }
   | { type: ActionTypes.Search; value: string }
@@ -101,6 +107,10 @@ let reducers: {
     if (state.disabled === action.disabled) return state
     return { ...state, disabled: action.disabled }
   },
+  [ActionTypes.SetOrientation](state, action) {
+    if (state.orientation === action.orientation) return state
+    return { ...state, orientation: action.orientation }
+  },
   [ActionTypes.GoToOption](state, action) {
     if (state.disabled) return state
     if (state.listboxState === ListboxStates.Closed) return state
@@ -193,16 +203,20 @@ export function Listbox<TTag extends ElementType = typeof DEFAULT_LISTBOX_TAG, T
     value: TType
     onChange(value: TType): void
     disabled?: boolean
+    horizontal?: boolean
   }
 ) {
-  let { value, onChange, disabled = false, ...passThroughProps } = props
+  let { value, onChange, disabled = false, horizontal = false, ...passThroughProps } = props
+  const orientation = horizontal ? 'horizontal' : 'vertical'
+
   let reducerBag = useReducer(stateReducer, {
     listboxState: ListboxStates.Closed,
     propsRef: { current: { value, onChange } },
     labelRef: createRef(),
     buttonRef: createRef(),
     optionsRef: createRef(),
     disabled,
+    orientation,
     options: [],
     searchQuery: '',
     activeOptionIndex: null,
@@ -216,6 +230,9 @@ export function Listbox<TTag extends ElementType = typeof DEFAULT_LISTBOX_TAG, T
     propsRef.current.onChange = onChange
   }, [onChange, propsRef])
   useIsoMorphicEffect(() => dispatch({ type: ActionTypes.SetDisabled, disabled }), [disabled])
+  useIsoMorphicEffect(() => dispatch({ type: ActionTypes.SetOrientation, orientation }), [
+    orientation,
+  ])
 
   // Handle outside click
   useWindowEvent('mousedown', event => {
@@ -413,6 +430,7 @@ interface OptionsRenderPropArg {
 type OptionsPropsWeControl =
   | 'aria-activedescendant'
   | 'aria-labelledby'
+  | 'aria-orientation'
   | 'id'
   | 'onKeyDown'
   | 'role'
@@ -478,12 +496,12 @@ let Options = forwardRefWithAs(function Options<
           disposables().nextFrame(() => state.buttonRef.current?.focus({ preventScroll: true }))
           break
 
-        case Keys.ArrowDown:
+        case match(state.orientation, { vertical: Keys.ArrowDown, horizontal: Keys.ArrowRight }):
           event.preventDefault()
           event.stopPropagation()
           return dispatch({ type: ActionTypes.GoToOption, focus: Focus.Next })
 
-        case Keys.ArrowUp:
+        case match(state.orientation, { vertical: Keys.ArrowUp, horizontal: Keys.ArrowLeft }):
           event.preventDefault()
           event.stopPropagation()
           return dispatch({ type: ActionTypes.GoToOption, focus: Focus.Previous })
@@ -535,6 +553,7 @@ let Options = forwardRefWithAs(function Options<
     'aria-activedescendant':
       state.activeOptionIndex === null ? undefined : state.options[state.activeOptionIndex]?.id,
     'aria-labelledby': labelledby,
+    'aria-orientation': state.orientation,
     id,
     onKeyDown: handleKeyDown,
     role: 'listbox',

packages/@headlessui-react/src/test-utils/accessibility-assertions.ts

@@ -263,9 +263,12 @@ export function assertListbox(
     attributes?: Record<string, string | null>
     textContent?: string
     state: ListboxState
+    orientation?: 'horizontal' | 'vertical'
   },
   listbox = getListbox()
 ) {
+  let { orientation = 'vertical' } = options
+
   try {
     switch (options.state) {
       case ListboxState.InvisibleHidden:
@@ -274,6 +277,7 @@ export function assertListbox(
         assertHidden(listbox)
 
         expect(listbox).toHaveAttribute('aria-labelledby')
+        expect(listbox).toHaveAttribute('aria-orientation', orientation)
         expect(listbox).toHaveAttribute('role', 'listbox')
 
         if (options.textContent) expect(listbox).toHaveTextContent(options.textContent)
@@ -289,6 +293,7 @@ export function assertListbox(
         assertVisible(listbox)
 
         expect(listbox).toHaveAttribute('aria-labelledby')
+        expect(listbox).toHaveAttribute('aria-orientation', orientation)
         expect(listbox).toHaveAttribute('role', 'listbox')
 
         if (options.textContent) expect(listbox).toHaveTextContent(options.textContent)

packages/@headlessui-vue/src/components/listbox/listbox.ts

@@ -38,9 +38,12 @@ type StateDefinition = {
   // State
   listboxState: Ref<ListboxStates>
   value: ComputedRef<unknown>
+  orientation: Ref<'vertical' | 'horizontal'>
+
   labelRef: Ref<HTMLLabelElement | null>
   buttonRef: Ref<HTMLButtonElement | null>
   optionsRef: Ref<HTMLDivElement | null>
+
   disabled: Ref<boolean>
   options: Ref<{ id: string; dataRef: ListboxOptionDataRef }[]>
   searchQuery: Ref<string>
@@ -79,6 +82,7 @@ export let Listbox = defineComponent({
   props: {
     as: { type: [Object, String], default: 'template' },
     disabled: { type: [Boolean], default: false },
+    horizontal: { type: [Boolean], default: false },
     modelValue: { type: [Object, String, Number, Boolean] },
   },
   setup(props, { slots, attrs, emit }) {
@@ -95,6 +99,7 @@ export let Listbox = defineComponent({
     let api = {
       listboxState,
       value,
+      orientation: computed(() => (props.horizontal ? 'horizontal' : 'vertical')),
       labelRef,
       buttonRef,
       optionsRef,
@@ -206,7 +211,7 @@ export let Listbox = defineComponent({
     return () => {
       let slot = { open: listboxState.value === ListboxStates.Open, disabled: props.disabled }
       return render({
-        props: omit(props, ['modelValue', 'onUpdate:modelValue', 'disabled']),
+        props: omit(props, ['modelValue', 'onUpdate:modelValue', 'disabled', 'horizontal']),
         slot,
         slots,
         attrs,
@@ -362,6 +367,7 @@ export let ListboxOptions = defineComponent({
           ? undefined
           : api.options.value[api.activeOptionIndex.value]?.id,
       'aria-labelledby': dom(api.labelRef)?.id ?? dom(api.buttonRef)?.id,
+      'aria-orientation': api.orientation.value,
       id: this.id,
       onKeydown: this.handleKeyDown,
       role: 'listbox',
@@ -410,12 +416,15 @@ export let ListboxOptions = defineComponent({
           nextTick(() => dom(api.buttonRef)?.focus({ preventScroll: true }))
           break
 
-        case Keys.ArrowDown:
+        case match(api.orientation.value, {
+          vertical: Keys.ArrowDown,
+          horizontal: Keys.ArrowRight,
+        }):
           event.preventDefault()
           event.stopPropagation()
           return api.goToOption(Focus.Next)
 
-        case Keys.ArrowUp:
+        case match(api.orientation.value, { vertical: Keys.ArrowUp, horizontal: Keys.ArrowLeft }):
           event.preventDefault()
           event.stopPropagation()
           return api.goToOption(Focus.Previous)

packages/@headlessui-vue/src/test-utils/accessibility-assertions.ts

@@ -263,9 +263,12 @@ export function assertListbox(
     attributes?: Record<string, string | null>
     textContent?: string
     state: ListboxState
+    orientation?: 'horizontal' | 'vertical'
   },
   listbox = getListbox()
 ) {
+  let { orientation = 'vertical' } = options
+
   try {
     switch (options.state) {
       case ListboxState.InvisibleHidden:
@@ -274,6 +277,7 @@ export function assertListbox(
         assertHidden(listbox)
 
         expect(listbox).toHaveAttribute('aria-labelledby')
+        expect(listbox).toHaveAttribute('aria-orientation', orientation)
         expect(listbox).toHaveAttribute('role', 'listbox')
 
         if (options.textContent) expect(listbox).toHaveTextContent(options.textContent)
@@ -289,6 +293,7 @@ export function assertListbox(
         assertVisible(listbox)
 
         expect(listbox).toHaveAttribute('aria-labelledby')
+        expect(listbox).toHaveAttribute('aria-orientation', orientation)
         expect(listbox).toHaveAttribute('role', 'listbox')
 
         if (options.textContent) expect(listbox).toHaveTextContent(options.textContent)