localized-strings

localized-strings

Simple module to localize the strings of any JS based program using the same syntax used in the ReactLocalization module and ReactNativeLocalization module libraries.

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.

It's possible to configure the library to use a specific routine that return the interface language, so it's possible to extend it in any possible environment.

Installation

npm install --save localized-strings

Usage

In the 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 'localized-strings';

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.

console.log ("HOW: " + strings.how);

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"
  }
})

You can also only overwrite a specific language using:

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

Custom getInterfaceLanguage method

You can pass a custom method to get the current interface based on the context.

The default method check the browser language but it could be replaced with other check if you are in a Server, ReactNative or Nativescript project.

The getInterfaceLanguage method can be as simple as:

 function getCustomInterfaceLanguage(){
   return "it-IT";
 }
 
 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"
  }
}, getCustomInterfaceLanguage)

Nativescript example

This is how you can use the library in a Nativescript project

const platform = require("platform");
this.strings = new LocalizedStrings({
            it: {
                score: "Punti",
                time: "Tempo"
            },
            en: {
                score: "Score",
                time: "Time"
            }
        }, () => {
            return platform.device.language;
        }
        );

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() - to format the passed 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)

  // 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
  })

Beware: do not define a string key as formatString!

• setContent(props) - to dynamically load another set of strings
• 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:

1. defining an Interface that extends the LocalizedStringsMethods interface and has all the object string's keys
2. 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.