Formatting and right to left

Dates, numbers and currency

Angular's date, number, percent and currency pipes use LOCALE_ID and Angular's locale data. @angular/common does not call Intl, so Hermes and browsers behave alike without polyfills. English is built in; register other languages once, as localisation.ts does with registerLocaleData(localeFr). With LOCALE_ID set to fr:

<text>{{ when | date: 'longDate' }}</text>
<!-- 24 septembre 2026 -->
<text>{{ 1234567.891 | number: '1.0-2' }}</text>
<!-- 1 234 567,89 -->
<text>{{ 1234.5 | currency: 'EUR' }}</text>
<!-- 1 234,50 € -->

French uses narrow and non-breaking spaces, as in a browser. For regional variants (fr-CA, en-GB), register the matching @angular/common/locales/ data file and use the full LOCALE_ID tag.

Timezones

date accepts the same timezones as in a browser through its third argument: offsets such as '+0530' or '-05:00', 'UTC', 'GMT', and North American abbreviations such as 'EST' or 'PDT'. mount() adds support to Hermes' Date.parse for the legacy date form Angular uses to determine the offset.

<text>{{ when | date: 'HH:mm' : 'UTC' }}</text>
<!-- 14:30 -->
<text>{{ when | date: 'HH:mm' : '+0500' }}</text>
<!-- 19:30 -->

Angular does not support named zones such as 'Europe/London', in browsers or here. The pipe uses the device's zone and logs a development warning once, naming the unsupported zone. For named zones, use Intl.DateTimeFormat with timeZone, supported by Hermes:

new Intl.DateTimeFormat('en-GB', { timeZone: 'Asia/Tokyo', timeStyle: 'short' }).format(when);
// '23:30'

Hermes supports only part of Intl, affecting direct callers. The iOS Hermes framework used here provides Intl.Collator, Intl.DateTimeFormat and Intl.NumberFormat, but no Intl.PluralRules, Intl.RelativeTimeFormat or Intl.ListFormat. Hence Localisation uses i18nPlural. Check missing APIs before using them, for example 'PluralRules' in Intl.

Angular's locale data excludes user clock and calendar preferences; an English speaker may use a 24-hour clock. Locale.calendars() exposes uses24hourClock, firstWeekday and timeZone to help choose formats such as 'HH:mm' instead of 'shortTime'.

Right to left

The platform sets direction at startup, independently of translations. Enable supportsRTL in the same plugin entry to lay out a right-to-left language correctly:

["expo-localization", { "supportedLocales": ["en", "ar"], "supportsRTL": true }]

React Native chooses direction from the device language at startup; it cannot change while the app runs. The cascade mirrors padding, text alignment and row-child order without stylesheet changes. For TypeScript-calculated positions, such as a drawer's opening edge or a slider's drag direction, use Direction from @ng-native/device. Locale.rtl() reports language direction; branch on Direction for the actual layout.