stefalda/react-localization

README

react-localization

Simple module to localize the React interface using the same syntax used in the ReactNativeLocalization module.

React 19 support

Version 2.0 has been recreated to support React 19, removing babel and adding vite tooling.

If you work with previous versions of react you can use version 1.x.

Note about version 1.x

This library has been refactored to use the newly created localized-strings package, now added as a dependency, so to unify the code and make it easier to mantain

All the basic code is now in the localized-strings project but this React version add support for embedding JSX code in the formatted strings, by overriding the formatString method.

How it works

The library uses the current interface language, then it loads and displays the strings matching the current interface locale or the default language (the first one if a match is not found) if a specific localization can't be found.

It's possible to force a language different from the interface one.

Installation

npm install --save react-localization

Usage

In the React class that you want to localize, require the library and define the strings object passing to the constructor a simple object containing a language key (i.e. en, it, fr..) and then a list of key-value pairs with the needed localized strings.

// ES6 module syntax
import LocalizedStrings from "react-localization";

let strings = new LocalizedStrings({
  en: {
    how: "How do you want your egg today?",
    boiledEgg: "Boiled egg",
    softBoiledEgg: "Soft-boiled egg",
    choice: "How to choose the egg",
  },
  it: {
    how: "Come vuoi il tuo uovo oggi?",
    boiledEgg: "Uovo sodo",
    softBoiledEgg: "Uovo alla coque",
    choice: "Come scegliere l'uovo",
  },
});

Then use the strings object literal directly in the render method accessing the key of the localized string.

<Text style={styles.title}>
  {strings.how}
</Text>;

The first language is considered the default one, so if a translation is missing for the selected language, the default one is shown and a line is written to the log as a reminder.

Update / Overwrite Locale

You might have default localized in the build but then download the latest localization strings from a server. Use setContent to overwrite the whole object.

NOTE that this will remove all other localizations if used.

strings.setContent({
  en: {
    how: "How do you want your egg todajsie?",
    boiledEgg: "Boiled eggsie",
    softBoiledEgg: "Soft-boiled egg",
    choice: "How to choose the egg",
  },
});

API

setLanguage(languageCode) - to force manually a particular language
getLanguage() - to get the current displayed language
getInterfaceLanguage() - to get the current device interface language
formatString() - formats the input string and returns a new string, replacing its placeholders with the other arguments strings

  en:{
    bread:"bread",
    butter:"butter",
    question:"I'd like {0} and {1}, or just {0}"
    ...
    login: 'login',
    onlyForMembers: 'You have to {0} in order to use our app',
    bold: 'bold',
    iAmText: 'I am {0} text',
    ...
    january: 'January',
    currentDate: 'The current date is {month} {day}, {year}!'
  }
  ...
  strings.formatString(strings.question, strings.bread, strings.butter)

  // React components can be used as placeholder values! Useful when using links or customizing style
  strings.formatString(strings.onlyForMembers, <a href="http://login.com">{strings.login}</a>)
  strings.formatString(strings.iAmText, <b>{strings.bold}</b>)

  // Named tokens can also be used to give some extra context to the format strings
  // You cannot mix tokens, something like formatString('{0}, {name}', 'Hello', {name: 'Bob'}) won't work
  strings.formatString(strings.currentDate, {
    month: strings.january,
    day: 12,
    year: 2018
  })

  // A key can also be passed directly (dot-notation is supported)
  strings.formatString('fridge.bread')

  // Other localized strings can be referenced with $ref{key}
  // en: { bread: 'bread', questionWithReferences: 'I\'d like $ref{bread}' }
  strings.formatString(strings.questionWithReferences)

Typical usage is to render it in a JSX with formatString calls inlined:

<div>
  <SomeComponent
    food={strings.formatString(strings.question, strings.bread, "jam")}
  />
  <p>
    Usage with an object parameter:{" "}
    {strings.formatString(strings.currentDate, {
      month: "February",
      day: 13,
      year: 2050,
    })}>
  </p>
</div>;

Beware: do not define a string key as formatString!

setContent(props) - to dynamically load another set of strings
getContent() - to get the whole content object (all languages/strings)
getString(key, language?, omitWarning?) - to get a single string, dot-notation supported
getAvailableLanguages() - to get an array of the languages passed in the constructor

Examples

To force a particular language use something like this:

_onSetLanguageToItalian() {
  strings.setLanguage('it');
  this.setState({});
}

Typescript support

Because of the dynamically generated class properties, it's a little tricky to have the autocomplete functionality working.

Anyway it's possible to gain the desired results by:

defining an Interface that extends the LocalizedStringsMethods interface and has all the object string's keys
defining that the LocalizedStrings instance implements that interface

This is the suggested solution to work with Typescript:

export interface IStrings extends LocalizedStringsMethods{
    score:string;
    time: String;
}

public strings: IStrings;
this.strings = new LocalizedStrings({
            it: {
                score: "Punti",
                time: "Tempo"
            },
            en: {
                score: "Score",
                time: "Time"
            }
        });

Questions or suggestions?

Feel free to contact me on Twitter or open an issue.