use i18n-2 in node.js outside of res scope

Question

Im trying to aim so i can use i18n within functions that is called.

I have the error:

(node:15696) UnhandledPromiseRejectionWarning: TypeError: i18n.__ is not a function

How can i make so i18n would work inside functions and dont have to be within a req?

Server.js:

var    i18n = require('i18n-2');

global.i18n = i18n;
i18n.expressBind(app, {
    // setup some locales - other locales default to en silently
    locales: ['en', 'no'],
    // change the cookie name from 'lang' to 'locale'
    cookieName: 'locale'
});

app.use(function(req, res, next) {
    req.i18n.setLocaleFromCookie();
    next();
});

//CALL another file with some something here.

otherfile.js:

somefunction() {
               message = i18n.__("no_user_to_select") + "???";

}

How should i solve this?

Answer 1

If you read the docs carefull under Using with Express.js, it's clearly documented how it's used. After you bind i18n to express app through i18n.expressBind, i18n is available through the req object available to all express middlewares like:

req.i18n.__("My Site Title")

So somefunction should either be a middleware like:

function somefunction(req, res, next) {
  // notice how its invoked through the req object
  const message = req.i18n.__("no_user_to_select") + "???";
  // outputs -> no_user_to_select???
}

Or you need to explicitly pass in the req object through a middleware like:

function somefunction(req) {
  const message = req.i18n.__("no_user_to_select") + "???";
  // outputs -> no_user_to_select???
}

app.use((req, res, next) => {
  somefunction(req);
});

If you want to use i18n directly you need to instantiate it as documented like

const I18n = require('i18n-2');

// make an instance with options
var i18n = new I18n({
    // setup some locales - other locales default to the first locale
    locales: ['en', 'de']
});

// set it to global as in your question
// but many advise not to use global
global.i18n = i18n;

// use anywhere
somefunction() {
  const message = i18n.__("no_user_to_select") + "???";
  // outputs -> no_user_to_select???
}

Many discourage use of global.

// international.js
// you can also export and import
const I18n = require('i18n-2');

// make an instance with options
var i18n = new I18n({
    // setup some locales - other locales default to the first locale
    locales: ['en', 'de']
});

module.exports = i18n;

// import wherever necessary
const { i18n } = require('./international');