I grew frustrated trying to deal with FormatJS, react-intl et al, and wrote a simple wrapper around polyglot, numeral and moment js to localise a React app.

i18n.js

// Simple i18n wrapper around polyglot, numeral and moment libraries:
//   http://airbnb.io/polyglot.js/
//   http://numeraljs.com/
//   http://momentjs.com/
//
// This is to achieve goals:
// 1. Have a locale message storage that can be decomposed into subsets,
//    and passed down the dependency chain. Think providing a subset of locale
//    strings to child components.
// 2. Centralise configuration, and normalise API of both moment and numeral
//    libraries.
//
// Usage:
//
// import i18n from './i18n';
// const locale = i18n('ru', { greetings: { hello: 'Привет, %{username}!' } });
// const greets = locale.ns('greetings');
// const string = greets.t('hello', { username: 'Einstein' });
// const number = greets.numeral.set(100000).format('0,000.00');
// const datetime = greets.moment.set('2016-01-01').format('LLLL');
//
// Subset and the original objects are functionally equivalent, and either one
// can be used for number and time formatting - making it easy to use subset
// objects injected as dependencies.
//
// See tests below for more usage examples.

import Polyglot from 'node-polyglot';
import moment from 'moment';

import numeralRU from 'numeral/languages/ru';
import numeral from 'numeral';
numeral.language('ru', numeralRU);

const i18n = (locale, phrases) => {
  const polyglot = new Polyglot({ locale, phrases });

  const localiser = (prefix) => ({
    locale,
    numeral: (x) => numeral.language(locale) && numeral(x),
    moment: (x) => moment(x).locale(locale),
    toString() { return prefix; },
    t(key, opts) { return polyglot.t(`${prefix}${key}`, opts); },
    ns(str) { return localiser(`${prefix}${str}.`); }
  });

  return localiser('');
};

export default i18n;

i18n_test.js

import { test } from 'ava';
import i18n from '../i18n';

test('basic translation', t => {
  const locale = i18n('ru', { boo: 'Boo Boo' });
  t.is(locale.t('boo'), 'Boo Boo');
});

test('namespace extraction', t => {
  const locale = i18n('ru', { boo: { woo: { moo: 'Moo Moo' } } });
  const woo = locale.ns('boo').ns('woo');
  t.is(woo.t('moo'), 'Moo Moo');
});

test('interpolation', t => {
  const locale = i18n('ru', { boo: 'Hi there %{username}' });
  t.is(locale.t('boo', { username: 'mrfreeman' }), 'Hi there mrfreeman');
});

test('pluralization', t => {
  const locale = i18n('ru', { boo: 'One thing |||| Many things' });
  t.is(locale.t('boo', 1), 'One thing');
  t.is(locale.t('boo', 2), 'Many things');
});

test('numeral js integration', t => {
  // note the order - numeral only has a global language,
  // so we can't mix it as we can with momentjs
  const ru = i18n('ru', { });
  const en = i18n('en', { });

  t.is(ru.numeral(10000).format('0,000.00'), '10 000,00');
  t.is(en.numeral(10000).format('0,000.00'), '10,000.00');
});

test('moment js integration', t => {
  const ru = i18n('ru', { });
  const en = i18n('en', { });

  t.is(ru.moment('2016-01-01').format('L'), '01.01.2016');
  t.is(en.moment('2016-01-01').format('L'), '01/01/2016');
});