Locale

Both of expo-localization's getters are synchronous, so unlike the rest of the device-state services there is no default to sit at while the platform answers. What makes this worth a service is that the answers change: a user can switch language in Settings and come back, and a date that was formatted correctly a moment ago is then wrong. Locale subscribes to that; nothing else in the package does.

Install

npx expo install expo-localization

import { Locale } from '@ng-native/expo/locale';

The smallest useful example

import { Component, computed, inject } from '@angular/core';
import { Locale } from '@ng-native/expo/locale';

@Component({
  selector: 'app-date',
  template: `<text>{{ formatted() }}</text>`,
})
export class Date {
  private readonly locale = inject(Locale);
  protected readonly formatted = computed(() =>
    new Intl.DateTimeFormat(this.locale.tag()).format(new globalThis.Date()),
  );
}

What it reports

• locales - every preferred locale, most preferred first, always at least one entry. That ordering is the reason to prefer this over a single locale string: an app that supports the user's second language should use it rather than fall back to English.
• locale - the first entry of locales, the one to format with. Null before anything is installed.
• calendars - the user's calendar preferences: calendar, timeZone, uses24hourClock, firstWeekday.
• rtl - whether the preferred locale reads right to left. This is a layout decision, not a translation one, which is why it is worth a signal of its own rather than folding into locale.
• tag - the preferred locale's language tag, the string Intl wants. undefined rather than a guess when nothing has been reported yet.

When it updates

expo-localization does not export the listeners its own hooks use internally, and a language or calendar change happens in Settings, outside the app. So Locale re-reads when the app comes back to the foreground, which is exactly when the answer can have changed - a public API (AppState) rather than a path into a build directory.

Without the module installed

locales and calendars are empty arrays, locale is null, rtl is false, tag is undefined.

Reference