This is documentation for the next SDK version. For up-to-date documentation, see the latest version (SDK 53).

Expo Localization

GitHub

npm

A library that provides an interface for native user localization information.

Android

iOS

tvOS

Web

expo-localization allows you to Localize your app, customizing the experience for specific regions, languages, or cultures. It also provides access to the locale data on the native device. Using a localization library such as lingui-js, react-i18next, react-intl or i18n-js with expo-localization will enable you to create a very accessible experience for users.

Installation

Terminal

- npx expo install expo-localization

If you are installing this in an existing React Native app, make sure to install expo in your project.

Configuration in app config

You can configure expo-localization using its built-in config plugin if you use config plugins in your project (EAS Build or npx expo run:[android|ios]). The plugin allows you to configure various properties that cannot be set at runtime and require building a new app binary to take effect.

Example app.json with config plugin

app.json

{
  "expo": {
    "plugins": ["expo-localization"]
  }
}

Usage

Find more information about using expo-localization and adding support for right-to-left languages in the Localization guide.

API

import { getLocales, getCalendars } from 'expo-localization';

Behavior

You can use synchronous getLocales() and getCalendars() methods to get the locale settings of the user device. On iOS, the results will remain the same while the app is running.

On Android, the user can change locale preferences in Settings without restarting apps. To keep the localization current, you can rerun the getLocales() and getCalendars() methods every time the app returns to the foreground. Use AppState to detect this.

Hooks

`useCalendars()`

Android

iOS

tvOS

Web

A hook providing a list of user's preferred calendars, returned as an array of objects of type Calendar. Guaranteed to contain at least 1 element. For now always returns a single element, but it's likely to return a user preference list on some platforms in the future. If the OS settings change, the hook will rerender with a new list of calendars.

Returns:

Calendar[]

Example

[{
  "calendar": "gregory",
  "timeZone": "Europe/Warsaw",
  "uses24hourClock": true,
  "firstWeekday": 1
}]

`useLocales()`

Android

iOS

tvOS

Web

A hook providing a list of user's locales, returned as an array of objects of type Locale. Guaranteed to contain at least 1 element. These are returned in the order the user defines in their device settings. On the web currency and measurements systems are not provided, instead returned as null. If needed, you can infer them from the current region using a lookup table. If the OS settings change, the hook will rerender with a new list of locales.

Returns:

Locale[]

Example

[{
  "languageTag": "pl-PL",
  "languageCode": "pl",
  "textDirection": "ltr",
  "digitGroupingSeparator": " ",
  "decimalSeparator": ",",
  "measurementSystem": "metric",
  "currencyCode": "PLN",
  "currencySymbol": "zł",
  "regionCode": "PL",
  "temperatureUnit": "celsius"
}]

Methods

`Localization.getCalendars()`

Android

iOS

tvOS

Web

List of user's preferred calendars, returned as an array of objects of type Calendar. Guaranteed to contain at least 1 element. For now always returns a single element, but it's likely to return a user preference list on some platforms in the future.

Returns:

Calendar[]

Example

[{
  "calendar": "gregory",
  "timeZone": "Europe/Warsaw",
  "uses24hourClock": true,
  "firstWeekday": 1
}]

`Localization.getLocales()`

Android

iOS

tvOS

Web

List of user's locales, returned as an array of objects of type Locale. Guaranteed to contain at least 1 element. These are returned in the order the user defines in their device settings. On the web currency and measurements systems are not provided, instead returned as null. If needed, you can infer them from the current region using a lookup table.

Returns:

Locale[]

Example

[{
  "languageTag": "pl-PL",
  "languageCode": "pl",
  "textDirection": "ltr",
  "digitGroupingSeparator": " ",
  "decimalSeparator": ",",
  "measurementSystem": "metric",
  "currencyCode": "PLN",
  "currencySymbol": "zł",
  "regionCode": "PL",
  "temperatureUnit": "celsius"
}]

Types

`Calendar`

Android

iOS

tvOS

Web

Property	Type	Description
calendar	`CalendarIdentifier \| null`	The calendar identifier, one of Unicode calendar types. On Android is limited to one of device's available calendar types. On iOS uses calendar identifiers, but maps them to the corresponding Unicode types, will also never contain `'dangi'` or `'islamic-rgsa'` due to it not being implemented on iOS.
firstWeekday	`Weekday \| null`	The first day of the week. For most calendars Sunday is numbered `1`, with Saturday being number `7`. Can be null on some browsers that don't support the weekInfo property in Intl API. Example `1`, `7`.
timeZone	`string \| null`	Time zone for the calendar. Can be `null` on Web. Example `'America/Los_Angeles'`, `'Europe/Warsaw'`, `'GMT+1'`.
uses24hourClock	`boolean \| null`	True when current device settings use 24-hour time format. Can be null on some browsers that don't support the hourCycle property in Intl API.

`Locale`

Android

iOS

tvOS

Web

Property	Type	Description
currencyCode	`string \| null`	Currency code for the locale. On iOS, it's the currency code from the `Region` setting under Language & Region, not for the current locale. On Android, it's the currency specifc to the locale in the list, as there are no separate settings for selecting a region. Is `null` on Web, use a table lookup based on region instead. Example `'USD'`, `'EUR'`, `'PLN'`.
currencySymbol	`string \| null`	Currency symbol for the currency specified by `currencyCode`. Example `'$'`, `'€'`, `'zł'`.
decimalSeparator	`string \| null`	Decimal separator used for formatting numbers with fractional parts. Example `'.'`, `','`.
digitGroupingSeparator	`string \| null`	Digit grouping separator used for formatting large numbers. Example `'.'`, `','`.
languageCode	`string \| null`	An IETF BCP 47 language tag without the region code. Example `'en'`, `'es'`, `'pl'`.
languageCurrencyCode	`string \| null`	Currency code for the locale. On iOS, it's the currency code for the current locale in the list, not the device region. On Android, it's equal to `currencyCode`. Is `null` on Web. Prefer using `currencyCode` for any internalization purposes. Example `'USD'`, `'EUR'`, `'PLN'`.
languageCurrencySymbol	`string \| null`	Currency symbol for the currency specified by `languageCurrencyCode`. Prefer using `currencySymbol` for any internalization purposes. Example `'$'`, `'€'`, `'zł'`.
languageRegionCode	`string \| null`	The region code for the preferred language. When the language is not region-specific, it returns the same value as `regionCode`. When the language is region-specific, it returns the region code for the language (`en-CA` -> `CA`). Prefer using `regionCode` for any internalization purposes. Example `'US'`.
languageScriptCode	`string \| null`	An ISO 15924 4-letter script code. On Android and Web, it may be `null` if none is defined. Example `'Latn'`, `'Hans'`, `'Hebr'`.
languageTag	`string`	An IETF BCP 47 language tag with a region code. Example `'en-US'`, `'es-419'`, `'pl-PL'`.
measurementSystem	`'metric' \| 'us' \| 'uk' \| null`	The measurement system used in the locale. Is `null` on Web, as user chosen measurement system is not exposed on the web and using locale to determine measurement systems is unreliable. Ask for user preferences if possible.
regionCode	`string \| null`	The region code for your device that comes from the Region setting under Language & Region on iOS, Region settings on Android and is parsed from locale on Web (can be `null` on Web). Example `'US'`.
temperatureUnit	`'celsius' \| 'fahrenheit' \| null`	The temperature unit used in the locale. Returns `null` if the region code is unknown.
textDirection	`'ltr' \| 'rtl' \| null`	Text direction for the locale. One of: `'ltr'`, `'rtl'`, but can also be `null` on some browsers without support for the textInfo property in Intl API.

Enums

`CalendarIdentifier`

Android

iOS

tvOS

Web

The calendar identifier, one of Unicode calendar types. Gregorian calendar is aliased and can be referred to as both CalendarIdentifier.GREGORIAN and CalendarIdentifier.GREGORY.

`BUDDHIST`

CalendarIdentifier.BUDDHIST ＝ "buddhist"

Thai Buddhist calendar

`CHINESE`

CalendarIdentifier.CHINESE ＝ "chinese"

Traditional Chinese calendar

`COPTIC`

CalendarIdentifier.COPTIC ＝ "coptic"

Coptic calendar

`DANGI`

CalendarIdentifier.DANGI ＝ "dangi"

Traditional Korean calendar

`ETHIOAA`

CalendarIdentifier.ETHIOAA ＝ "ethioaa"

Ethiopic calendar, Amete Alem (epoch approx. 5493 B.C.E)

`ETHIOPIC`

CalendarIdentifier.ETHIOPIC ＝ "ethiopic"

Ethiopic calendar, Amete Mihret (epoch approx, 8 C.E.)

`GREGORIAN`

CalendarIdentifier.GREGORIAN ＝ "gregory"

Gregorian calendar (alias)

`GREGORY`

CalendarIdentifier.GREGORY ＝ "gregory"

Gregorian calendar

`HEBREW`

CalendarIdentifier.HEBREW ＝ "hebrew"

Traditional Hebrew calendar

`INDIAN`

CalendarIdentifier.INDIAN ＝ "indian"

Indian calendar

`ISLAMIC`

CalendarIdentifier.ISLAMIC ＝ "islamic"

Islamic calendar

`ISLAMIC_CIVIL`

CalendarIdentifier.ISLAMIC_CIVIL ＝ "islamic-civil"

Islamic calendar, tabular (intercalary years [2,5,7,10,13,16,18,21,24,26,29] - civil epoch)

`ISLAMIC_RGSA`

CalendarIdentifier.ISLAMIC_RGSA ＝ "islamic-rgsa"

Islamic calendar, Saudi Arabia sighting

`ISLAMIC_TBLA`

CalendarIdentifier.ISLAMIC_TBLA ＝ "islamic-tbla"

Islamic calendar, tabular (intercalary years [2,5,7,10,13,16,18,21,24,26,29] - astronomical epoch)

`ISLAMIC_UMALQURA`

CalendarIdentifier.ISLAMIC_UMALQURA ＝ "islamic-umalqura"

Islamic calendar, Umm al-Qura

`ISO8601`

CalendarIdentifier.ISO8601 ＝ "iso8601"

ISO calendar (Gregorian calendar using the ISO 8601 calendar week rules)

`JAPANESE`

CalendarIdentifier.JAPANESE ＝ "japanese"

Japanese imperial calendar

`PERSIAN`

CalendarIdentifier.PERSIAN ＝ "persian"

Persian calendar

`ROC`

CalendarIdentifier.ROC ＝ "roc"

Civil (algorithmic) Arabic calendar

`Weekday`

Android

iOS

tvOS

Web

An enum mapping days of the week in Gregorian calendar to their index as returned by the firstWeekday property.

`SUNDAY`

Weekday.SUNDAY ＝ 1

`MONDAY`

Weekday.MONDAY ＝ 2

`TUESDAY`

Weekday.TUESDAY ＝ 3

`WEDNESDAY`

Weekday.WEDNESDAY ＝ 4

`THURSDAY`

Weekday.THURSDAY ＝ 5

`FRIDAY`

Weekday.FRIDAY ＝ 6

`SATURDAY`

Weekday.SATURDAY ＝ 7