svelte-i18n

Internationalization for Svelte.

• TODO - WIP
• Usage
  • Locale
  • The dictionary
  • Formatting
  • Formatting methods
  • Formats
• CLI
  • Options

TODO - WIP

• Maybe locale can be a promise so we can await for it on the template;
• Wiki on github;
• Find a more flexible way to preload dictionaries so it's possible to preload partial dictionaries.

Usage

svelte-i18n uses stores to keep track of the current locale, dictionary of messages and the main format function. This way, we keep everything neat, in sync and easy to use on your svelte files.

---

Locale

The locale store defines what is the current locale.

import { locale, dictionary, getClientLocale } from 'svelte-i18n'

// Set the current locale to en-US
locale.set('en-US')

// This is a store, so we can subscribe to its changes
locale.subscribe(() => console.log('locale change'))

// svelte-i18n exports a method to help getting the current client locale
locale.set(
  getClientLocale({
    // the fallback locale, if didn't find any
    fallback: 'en-US',
    // set to 'true' to check the 'window.navigator.language'
    navigator: true,
    // set the key name to look for a locale on 'window.location.search'
    // 'example.com?locale=en-US'
    search: 'lang',
    // set the key name to look for a locale on 'window.location.hash'
    // 'example.com#locale=en-US'
    hash: 'locale',
    // define a pattern to look in the window.location.pathname. It returns the first capturing group.
    pathname: /^\/(.*?)\//,
    // define a pattern to look in the window.location.hostname. It returns the first capturing group.
    hostname: /^\/(.*?)\//,
  })
)

If a locale with the format xx-YY is not found, svelte-i18n looks for the locale xx as well.

---

The dictionary

The dictionary store defines the dictionary of messages of all locales.

import { locale, dictionary } from 'svelte-i18n'

// Define a locale dictionary
dictionary.set({
  pt: {
    message: 'Mensagem',
    'switch.lang': 'Trocar idioma',
    greeting: {
      ask: 'Por favor, digite seu nome',
      message: 'Olá {name}, como vai?',
    },
    photos:
      'Você {n, plural, =0 {não tem fotos.} =1 {tem uma foto.} other {tem # fotos.}}',
    cats: 'Tenho {n, number} {n,plural,=0{gatos}one{gato}other{gatos}}',
  },
  en: {
    message: 'Message',
    'switch.lang': 'Switch language',
    greeting: {
      ask: 'Please type your name',
      message: 'Hello {name}, how are you?',
    },
    photos:
      'You have {n, plural, =0 {no photos.} =1 {one photo.} other {# photos.}}',
    cats: 'I have {n, number} {n,plural,one{cat}other{cats}}',
  },
})

// It's also possible to merge the current dictionary
// with other objets
dictionary.update(dict => {
  dict.fr = {
    // ...french messages
  }
  return dict
})

Each language message dictionary can be as deep as you want. Messages can also be looked up by a string represetation of it's path on the dictionary (i.e greeting.message).

---

Formatting

The _/format store is the actual formatter method. To use it it's simple as any other svelte store.

<script>
  // locale is en
  import { _ } from 'svelte-i18n'
</script>

<input placeholder="{$_('greeting.ask')}" />

svelte-i18n uses formatjs behind the scenes, which means it supports the ICU message format for interpolation, pluralization and much more.

<div>
  {$_('greeting.message', { values: { name: 'John' }})}
  <!-- Hello John, how are you? -->

  {$_('photos', { values: { n: 0 }})}
  <!-- You have no photos. -->

  {$_('photos', { values: { n: 12} })}
  <!-- You have 12 photos. -->
</div>

Formatting methods

_ / format

Main formatting method that formats a localized message by its id.

function(messageId: string, options?: MessageObject): string
function(options: MessageObject): string

interface MessageObject {
  id?: string
  locale?: string
  format?: string
  default?: string
  values?: Record<string, string | number | Date>
}

• id: represents the path to a specific message;
• locale: forces a specific locale;
• default: the default value in case of message not found in the current locale;
• format: the format to be used. See #formats;
• values: properties that should be interpolated in the message;

You can pass a string as the first parameter for a less verbose way of formatting a message.

<script>
  import { _ } from 'svelte-i18n'
</script>

<div>{$_('greeting.ask')}</div>
<!-- Please type your name -->

<div>{$_({ id: 'greeting.ask' })}</div>
<!-- Please type your name -->

The formatter method also provides some casing utilities:

• _.upper - transforms a localized message into uppercase;
• _.lower - transforms a localized message into lowercase;
• _.capital - capitalize a localized message;
• _.title - transforms the message into title case;

<div>{$_.upper('greeting.ask')}</div>
<!-- PLEASE TYPE YOUR NAME -->

<div>{$_.lower('greeting.ask')}</div>
<!-- please type your name -->

<div>{$_.capital('greeting.ask')}</div>
<!-- Please type your name -->

<div>{$_.title('greeting.ask')}</div>
<!-- Please Type Your Name -->

_.time

Formats a date object into a time string with the specified format (short, medium, long, full). Please refer to the #formats section to see available formats.

function(time: Date, options: MessageObject): string

<div>{$_.time(new Date(2019, 3, 24, 23, 45))}</div>
<!-- 11:45 PM -->

<div>{$_.time(new Date(2019, 3, 24, 23, 45), { format: 'medium' } )}</div>
<!-- 11:45:00 PM -->

_.date

Formats a date object into a string with the specified format (short, medium, long, full). Please refer to the #formats section to see available formats.

function(date: Date, options: MessageObject): string

<div>{$_.date(new Date(2019, 3, 24, 23, 45))}</div>
<!-- 4/24/19 -->

<div>{$_.date(new Date(2019, 3, 24, 23, 45), { format: 'medium' } )}</div>
<!-- Apr 24, 2019 -->

_.number

Formats a number with the specified locale and format. Please refer to the #formats section to see available formats.

function(number: number, options: MessageObject): string

<div>{$_.number(100000000)}</div>
<!-- 100,000,000 -->

<div>{$_.number(100000000, { locale: 'pt' })}</div>
<!-- 100.000.000 -->

Formats

svelte-i18n comes with a set of default number, time and date formats:

Number:

• currency: { style: 'currency' }
• percent: { style: 'percent' }
• scientific: { notation: 'scientific' }
• engineering: { notation: 'engineering' }
• compactLong: { notation: 'compact', compactDisplay: 'long' }
• compactShort: { notation: 'compact', compactDisplay: 'short' }

Date:

• short: { month: 'numeric', day: 'numeric', year: '2-digit' }
• medium: { month: 'short', day: 'numeric', year: 'numeric' }
• long: { month: 'long', day: 'numeric', year: 'numeric' }
• full: { weekday: 'long', month: 'long', day: 'numeric', year: 'numeric' }

Time:

• short: { hour: 'numeric', minute: 'numeric' }
• medium: { hour: 'numeric', minute: 'numeric', second: 'numeric' }
• long: { hour: 'numeric', minute: 'numeric', second: 'numeric', timeZoneName: 'short' }
• full: { hour: 'numeric', minute: 'numeric', second: 'numeric', timeZoneName: 'short' }

It's possible to define custom format styles via the addCustomFormats method if you need to supply a set of options to the underlying Intl formatter.

function addCustomFormats(formatsObject: Formats): void

interface Formats {
  number: Record<string, Intl.NumberFormatOptions>
  date: Record<string, Intl.DateTimeFormatOptions>
  time: Record<string, Intl.DateTimeFormatOptions>
}

Please refer to the Intl.NumberFormat and Intl.DateTimeFormat documentations to see available formatting options.

Example:

import { addCustomFormats } from 'svelte-i18n'

addCustomFormats({
  number: {
    EUR: {
      style: 'currency',
      currency: 'EUR',
    },
  },
})

<div>
  {$_.number(123456.789, { format: 'EUR' })}
</div>
<!-- 123.456,79 € -->

CLI

svelte-i18n provides a command-line interface to extract all your messages to the stdout or to a specific JSON file.

$ svelte-i18n extract [options] <glob-pattern> [output-file]

Options

• -s, --shallow - extract all messages to a shallow object, without creating nested objects. Default: false.

• --overwrite - overwrite the content of the output file instead of just appending missing properties. Default: false.

• -c, --configDir - define the directory of a svelte.config.js in case your svelte components need to be preprocessed.