Use React-Intl API outside React component

formatMessage.js

import { IntlProvider, defineMessages } from 'react-intl';

const language = 'en';
// Usually messages is declared in another file.
const messages = {
  greeting: 'Hello'
}
export const mesg = defineMessages({
  greeting: {
    id: 'greeting',
    defaultMessage: 'Whats up'
  }
});

const { intl } = new IntlProvider({ locale: language, messages: messages }, {}).getChildContext();
intl.formatMessage(mesg.greeting); // "Hello"
intl.formatNumber(1000); // "1,000"