useLocale

The useLocale composable provides comprehensive internationalization (i18n) capabilities, allowing you to manage multiple locales, switch between them dynamically, and translate messages with variable replacement and message linking. Built on createSingle for single-locale selection and supports custom adapters for integration with different i18n libraries.

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Intermediate95.8% coverageMar 3, 2026

Installation

Install the Locale plugin in your app’s entry point:

main.ts

import { createApp } from 'vue'
import { createLocalePlugin } from '@vuetify/v0'
import App from './App.vue'

const app = createApp(App)

app.use(
  createLocalePlugin({
    default: 'en',
    messages: {
      en: {
        hello: 'Hello',
        welcome: 'Welcome, {name}!',
      },
      es: {
        hello: 'Hola',
        welcome: '¡Bienvenido, {name}!',
      },
    },
  })
)

app.mount('#app')

Usage

Once the plugin is installed, use the useLocale composable in any component:

vue

<script setup lang="ts">
  import { useLocale } from '@vuetify/v0'

  const locale = useLocale()

  function changeLocale(id: string) {
    locale.select(id)
  }
</script>

<template>
  <div>
    <h1>{{ locale.t('hello') }}</h1>
    <p>{{ locale.t('welcome', { name: 'John' }) }}</p>

    <button @click="changeLocale('en')">English</button>
    <button @click="changeLocale('es')">Español</button>
    <button @click="changeLocale('fr')">Français</button>
  </div>
</template>

Architecture

useLocale extends createSingle for locale selection with message interpolation:

Reactivity

Locale selection is reactive via createSingle. Translation methods return static strings.

Property	Reactive	Notes
`selectedId`		Current locale ID
`selectedItem`		Current locale ticket
`selectedValue`		Current locale value
`selectedIndex`		Index in registry

API Reference

The following API details are for the useLocale composable.

Functions

createLocale

(_options?: LocaleOptions<TokenCollection>) => R

Creates a new locale instance.

createLocaleFallback

() => R

createLocaleContext

<_E>(_options?: LocaleContextOptions | undefined) => ContextTrinity<_E>

createLocalePlugin

(_options?: LocaleContextOptions | undefined) => Plugin

useLocale

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

Options

events

boolean | undefined

Enable event emission for registry operations

Default: false

reactive

boolean | undefined

Enable reactive behavior for registry operations

Default: false

disabled

MaybeRefOrGetter<boolean> | undefined

Disabled state for the entire model instance

Default: false

enroll

MaybeRefOrGetter<boolean> | undefined

Auto-select tickets on registration

Default: true

multiple

MaybeRefOrGetter<boolean> | undefined

Allow multiple tickets to be selected simultaneously

Default: false

mandatory

MaybeRefOrGetter<boolean | "force"> | undefined

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

default

ID | undefined

fallback

ID | undefined

messages

Record<ID, Z> | undefined

Properties

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

ComputedRef<ID | undefined>

selectedIndex

ComputedRef<number>

selectedItem

ComputedRef<E | undefined>

selectedValue

ComputedRef<E["value"] | undefined>

Methods

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"]) => 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>) => 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

Seek for a ticket based on direction and optional predicate

seek

(direction?: "first" | "last", from?: number, predicate?: (ticket) => boolean) => E | undefined

on

<K extends Extensible<RegistryEventName>>(event: K, cb: EventHandler<E, K>) => void

Listen for registry events

off

<K extends Extensible<RegistryEventName>>(event: K, cb: EventHandler<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[]) => void

Offboard multiple tickets at once

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?) => 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?: Record<string, unknown>, fallback?: string) => string

Translate a message key with optional parameters and fallback.

n

(value: number) => string

register

(registration?: Partial<Z>) => E