i18n (Internationalization)

Overview

This guide details how to use some of i18n library’s features. For an overview of the modules supplied with the library please see I18nDecorator and Uppercase. This library incorporates the iLib internationalization library.

Using I18nDecorator

I18nDecorator is a higher-order component (HOC) that provides easy access to locale information. Applications wishing to receive locale information can wrap the root component with the HOC. It is not necessary to use I18nDecorator directly for applications using MoonstoneDecorator.

The HOC works by passing locale information to the app through context and CSS classes. It contains three properties via context:

  • locale - a string representing the current locale
  • rtl - if true then the locale is a right-to-left language.
  • updateLocale - a function to update the locale of the app.

Accessing I18nDecorator context properties

The following example demonstrates using I18nContextDecorator with a component:

import {I18nContextDecorator} from '@enact/i18n/I18nDecorator';

const SomeComponent = I18nContextDecorator(
	{rtlProp: 'rtl'},
	(props) => (
		<div>Hello from the {context.rtl ? 'right' : 'left'}</div>
	)
);

Locale-Specific CSS

When the I18nDecorator wraps your app, it automatically applies some CSS classes to the root element. You can use these to write locale-specific CSS override classes using the global specifier. These classes may indicate things such as whether the locale uses a right-to-left orientation or whether it uses non-Latin fonts.

Classes added to the body include:

  • enact-locale-non-latin, if the locale uses a non-Latin font

  • enact-locale-right-to-left, if the locale is oriented right-to-left (in the absence of this class, the default orientation is left-to-right)

  • enact-locale-non-italic, if the locale uses a script that is not typically italicized, such as Chinese or Thai. (You may also use this in your own classes to enable or disable italicization.)

The following classes allow you to switch functionality based on the language, script, or region of the current UI locale:

  • enact-locale-<language>
  • enact-locale-<script>
  • enact-locale-<region>
  • enact-locale-<language>-<script>
  • enact-locale-<language>-<region>
  • enact-locale-<language>-<script>-<region>

So for United States English you would see this enact-locale-en enact-locale-en-US enact-locale-US.

Here’s an example from the Moonstone package in which locale-specific CSS is used to turn on right-to-left orientation for a widget:

	:global(.enact-locale-right-to-left) & {
		flex-direction: row-reverse;
	}

NOTE: We’re using LESS and CSS modules, which are supported by the enact command line tool

Translating Strings using $L()

$L() is a convenience function wrapping ilib/ResBundle that is exported by the main Enact library.

It can be used as follows:

import $L from '@enact/i18n/$L';

const translatedString = $L('Some String');

// You can also use it inside jsx
<Panel title={$L('Some Title')}>
	<div>{$L('Some Children')}</div>
	<div>{translatedString}</div>
</Panel>

In order for the translations to be successful, a locale-specific translation file must be available. If a suitable translation cannot be found, the original string will be returned.

Each translatable string in your application should be wrapped in a call to $L().

You will need to extract the strings inside the $L() calls in your source code and write them out to a strings.json file for each locale. (Most likely you’ll want to create a script to do this.)

The strings.json files should contain the translations in JSON format, i.e.:

	{
		"source string1": "translated string1",
		"source string2": "translated string2",
		...
	}

Many localization companies are able to provide translations in this format.

The string returned from a call to $L() will be the translated string for the current UI locale. If a different locale or a bundle with a different name is needed, use ResBundle directly instead of $L().

Updating Locale

If you wish to learn how to programmatically change the locale, please see Updating Locale.

iLib

iLib provides the locale-specific features of i18n. If you wish to learn about some of the other things it can do, like string translation, string/number formatting, etc., please see iLib Docs.

Sample

A sample i18n app is available here.