Angular 2+ - internationalization with Polyglot.js

i18n.service.js

import { Injectable } from '@angular/core';

const Polyglot = require('node-polyglot'); // https://www.npmjs.com/package/node-polyglot

// Example of pl_pl.json file: { "Hello world":"Witaj świecie" }
let dictionaries = {
    pl_pl: require('./pl_pl/pl_pl.json'),
    en_gb: require('./en_gb/en_gb.json')
};

@Injectable()
export class I18nService {
    private polyglot = null;

    constructor() {
        let locale = 'pl_pl';
        let phrases = dictionaries[locale];

        this.polyglot = new Polyglot({ locale, phrases });
    }

    translate(phrase) {
        return this.polyglot.t(phrase);
    }
}