# useLocale API

> Auto-generated API reference for `useLocale` from @vuetify/v0 (Vuetify0).
> Source of truth: https://0.vuetifyjs.com/api/use-locale

## Related

- https://0.vuetifyjs.com/composables/plugins/use-locale
- https://0.vuetifyjs.com/components/providers/locale
- https://0.vuetifyjs.com/guide/features/accessibility

## Functions

### createLocale

Creates a new locale instance.

```ts
(_options?: LocaleOptions<TokenCollection>) => LocaleContext<LocaleTicketInput, LocaleTicket<LocaleTicketInput>>
```

### createLocaleFallback

```ts
() => LocaleContext<LocaleTicketInput, LocaleTicket<LocaleTicketInput>>
```

### createLocaleContext

```ts
<_E>(_options?: LocalePluginOptions | undefined) => ContextTrinity<_E>
```

### createLocalePlugin

```ts
(_options?: LocalePluginOptions | undefined) => Plugin
```

### useLocale

```ts
<_E>(namespace?: string) => _E
```

## Options

| Name | Type | Default | Required | Description |
|---|---|---|---|---|
| `events` | `boolean \| undefined` | `false` | no | Enable event emission for registry operations |
| `reactive` | `boolean \| undefined` | `false` | no | Enable reactive behavior for registry operations |
| `disabled` | `MaybeRefOrGetter<boolean> \| undefined` | `false` | no | Disabled state for the entire model instance |
| `enroll` | `MaybeRefOrGetter<boolean> \| undefined` | `true` | no | Auto-select tickets on registration |
| `multiple` | `MaybeRefOrGetter<boolean> \| undefined` | `false` | no | Allow multiple tickets to be selected simultaneously |
| `mandatory` | `MaybeRefOrGetter<boolean \| "force"> \| undefined` | — | no | Controls mandatory selection behavior: - `false` (default): No mandatory selection enforcement - `true`: Prevents deselecting the last selected item - `'force'`: Automatically selects the first non-disabled item on registration |
| `adapter` | `LocaleAdapter \| undefined` | — | no | — |
| `default` | `ID \| undefined` | — | no | — |
| `fallback` | `ID \| undefined` | — | no | — |
| `messages` | `Record<ID, Z> \| undefined` | — | no | — |

## Methods

| Name | Type | Description |
|---|---|---|
| `clear` | `() => void` | Clear the entire registry |
| `has` | `(id: ID) => boolean` | Check if a ticket exists by ID |
| `keys` | `() => readonly ID[]` | Get all registered IDs |
| `browse` | `(value: E["value"]) => readonly ID[] \| undefined` | Browse for an ID(s) by value |
| `lookup` | `(index: number) => ID \| undefined` | Lookup a ticket by index number |
| `get` | `(id: ID) => E \| undefined` | Get a ticket by ID |
| `upsert` | `(id: ID, ticket?: Partial<Z>, event?: string) => E` | Update or insert a ticket by ID |
| `values` | `() => readonly E[]` | Get all values of registered tickets |
| `entries` | `() => readonly [ID, E][]` | Get all entries of registered tickets |
| `unregister` | `(id: ID) => void` | Unregister a ticket by ID |
| `reindex` | `() => void` | Reset the index directory and update all tickets |
| `move` | `(id: ID, toIndex: number) => E \| undefined` | Move a ticket to a new index position |
| `reorder` | `(ids: ID[]) => void` | Reorder the registry to match a canonical permutation of ids in one pass. |
| `seek` | `(direction?: "first" \| "last", from?: number, predicate?: (ticket: E) => boolean) => E \| undefined` | Seek for a ticket based on direction and optional predicate |
| `on` | `<K extends Extensible<RegistryEventName>>(event: K, cb: RegistryEventCallback<E, K>) => void` | Listen for registry events |
| `off` | `<K extends Extensible<RegistryEventName>>(event: K, cb: RegistryEventCallback<E, K>) => void` | Stop listening for registry events |
| `emit` | `<K extends Extensible<RegistryEventName>>(event: K, data: EventPayload<E, K>) => void` | Emit an event with data |
| `dispose` | `() => void` | Clears the registry and removes all listeners |
| `offboard` | `(ids: ID[]) => Partial<Z>[]` | Offboard multiple tickets at once, returning the input shapes that were removed. |
| `batch` | `<R>(fn: () => R) => R` | Execute operations in a batch, deferring cache invalidation and event emission until complete |
| `reset` | `() => void` | Reset selection state without destroying the registry |
| `select` | `(id: ID) => void` | Select a ticket by ID |
| `unselect` | `(id: ID) => void` | Unselect a ticket by ID |
| `toggle` | `(id: ID) => void` | Toggle a ticket's selection state |
| `selected` | `(id: ID) => boolean` | Check if a ticket is currently selected |
| `apply` | `(values: unknown[], options?: { multiple?: boolean; }) => void` | Apply external values to the model |
| `mandate` | `() => void` | Mandate selected ID based on "mandatory" option |
| `onboard` | `(registrations: Partial<Z>[]) => E[]` | Onboard multiple tickets at once |
| `t` | `(key: string, ...params: unknown[]) => string` | Translate a message key with optional parameters. |
| `ti` | `(key: string, ...params: unknown[]) => string \| undefined` | Translate a message key only if it exists, otherwise return `undefined`.  Unlike {@link t}, `ti` ("translate if exists") never echoes the raw key on a miss. This lets components supply their own inline English default with the nullish-coalescing operator instead of relying on bundled fallback messages. |
| `n` | `(value: number) => string` | — |
| `register` | `(registration?: Partial<Z>) => E` | Register a locale with optional messages.  When `messages` is provided, flattens them to dot-notation tokens and onboards them into the token registry before registering the locale for selection. |

## Properties

| Name | Type | Description |
|---|---|---|
| `collection` | `ReadonlyMap<ID, E>` | The collection of tickets in the registry |
| `size` | `number` | The number of tickets in the registry |
| `selectedIds` | `Reactive<Set<ID>>` | Set of currently selected ticket IDs |
| `selectedItems` | `ComputedRef<Set<E>>` | Computed Set of selected ticket instances |
| `selectedValues` | `ComputedRef<Set<E["value"] extends Ref<infer U, infer U> ? U : E["value"]>>` | Computed Set of selected ticket values |
| `disabled` | `MaybeRefOrGetter<boolean>` | Disabled state for the entire model instance |
| `multiple` | `MaybeRefOrGetter<boolean>` | Whether the selection allows multiple selections |
| `selectedId` | `Readonly<Ref<ID \| undefined, ID \| undefined>>` | — |
| `selectedIndex` | `Readonly<Ref<number, number>>` | — |
| `selectedItem` | `Readonly<Ref<E \| undefined, E \| undefined>>` | — |
| `selectedValue` | `Readonly<Ref<E["value"] \| undefined, E["value"] \| undefined>>` | — |