Lingua NPM | npm.io

Lingua

Lingua is a middleware for the Express.js framework that helps you to internationalise your webapp easily. It determines the language of the user agent and pushes the i18n resources to your views.

Installation

$ npm install lingua

Quick Start

Using lingua comes down with four simple steps:

Grab lingua

var express = require('express'),
    lingua  = require('lingua');

...
// Express init code goes here
...    

// Express app configuration code and lingua init.
app.configure(function() {
    ...
    app.set('views', __dirname + '/views');
    app.set('view engine', 'ejs');

    // Lingua configuration
    app.use(lingua(app, {
        defaultLocale: 'en',
        path: __dirname + '/i18n'
    }));

    app.use(express.bodyParser());
    app.use(express.methodOverride());
    app.use(express.static(__dirname + '/public'));
    app.use(app.router);

    ...
});

Note: Please ensure that the call: "app.use(app.router);" is the last entry in your configuration section.

Create i18n resource files - Note that you have to create a resource file for your default language. (In this example: './i18n/en.json' and './i18n/de-de.json').

// en.json
    {
        "title": "Hello World",
        "content": {
            "description": "A little description."
        }
    }

// de-de.json
    {
        "title": "Hallo Welt",
        "content": {
            "description": "Eine kleine Beschreibung."
        }
    }

a. Use lingua in your views - Static output - Note that the syntax depends on your template engine. In this example it is: ejs and the request comes from a browser which sends 'en' with the HTTP request header.
```
<h1><%= lingua.title %></h1> 
<p><%= lingua.content.description %></h1> 
```
b. Use lingua in your views - Dynamic output - Sometimes it is necessary to handle dynamic data within your express route and pass it to the template. What if your i18n resource includes placeholders ("{key}") within a string where you can put in your dynamic data? Well, it is possible. First of all, look at this i18n resource file:
```
// de.json
{
    "greeting": "Hallo {name}. Dieser Schlüssel {code} wurde für Dich generiert."
}
```
Now it is possible to transfer an object from your route into your template:
```
app.get('/', function(req, res) {
    var names = ['Sarah', 'Thomas', 'Claudia'];

    res.render('index', {
        person: {
            name: names[Math.floor(Math.random()*names.length)],
            code: Math.round(Math.random()*100)
        }
    });
});
```
And finally you can execute the i18n resource (yes, you can execute it (: ) and pass your data model to this function:
```
<p><%= lingua.greeting(person) %></p>
```
Note: Every i18n resource which contains placeholders like in the example above is a function after you've started the application.

Let the user select a language - Note that the user's selection is persisted within a cookie. This is an optional step. If you want to let lingua determine the user language from the browser configuration then leave this step out. Anyway, this is a very handy feature for switching the language by a user decision.

<a href="?language=de-DE">de-DE</a>
<a href="?language=en-US">en-US</a>

You can configure lingua in order to change the name of this parameter.

// Express app configuration code and lingua init.
app.configure(function() {
    ...

    // Lingua configuration
    app.use(lingua(app, {
        defaultLocale: 'en',
        path: __dirname + '/i18n',
        storageKey: 'lang' // http://domain.tld/?lang=de
    }));

    ...
});

The cookie lingua uses expires in one year, and includes the httpOnly flag to prevent clientside access from Javascript. You can override these settings by providing a cookieOptions key during configuration.

// Express app configuration code and lingua init.
app.configure(function() {
    ...

    // Lingua configuration
    app.use(lingua(app, {
        defaultLocale: 'en',
        path: __dirname + '/i18n',
        storageKey: 'lang', // http://domain.tld/?lang=de
        cookieOptions: {
            domain: '.domain.tld',    // to allow subdomains access to the same cookie, for instance
            path: '/blog',            // to restrict the language cookie to a path
            httpOnly: false,          // if you need access to this cookie from javascript on the client
            expires: new Date(Date.now() + 24 * 60 * 60 * 1000),  // expire in 1 day instead of 1 year
            secure: true              // for serving over https
        }
    }));

    ...
});