i18next

component.js

t('global_datetime_formatter', { date: myDate })

t('global_currency_formatter', { value: myValue })

i18next.js

import i18n from 'i18next'
import Backend from 'i18next-xhr-backend'
import LanguageDetector from 'i18next-browser-languagedetector'
import { reactI18nextModule } from 'react-i18next'

import * as R from 'ramda'

import dateFnsFormat from 'date-fns/format'

const getPattern = R.compose(
  R.prop(1),
  R.split('|')
)

i18n
  // load translation using xhr -> see /public/locales
  // learn more: https://github.com/i18next/i18next-xhr-backend
  .use(Backend)

  // detect user language
  // learn more: https://github.com/i18next/i18next-browser-languageDetector
  .use(LanguageDetector)

  // pass the i18n instance to react-i18next.
  // .use(initReactI18n)
  .use(reactI18nextModule)

  // init i18next
  // for all options read: https://www.i18next.com/overview/configuration-options
  .init({
    debug: false,
    fallbackLng: 'pt-BR',
    interpolation: {
      escapeValue: false, // not needed for react as it escapes by default
      format: (value, format, lang) => {
        if (R.or(R.isNil, R.isEmpty)(value)) {
          return ''
        }

        const getValue = R.cond([
          [
            R.contains('date'),
            R.compose(
              pattern => dateFnsFormat(value, pattern),
              getPattern
            )
          ],
          [
            R.contains('currency'),
            R.compose(
              pattern =>
                R.compose(
                  R.trim,
                  R.replace(' ', ''),
                  R.replace(' ', ''),
                  R.replace(pattern, ''),
                  pattern =>
                    new Intl.NumberFormat(lang, {
                      style: 'currency',
                      currency: pattern,
                      currencyDisplay: 'code'
                    }).format(value)
                )(pattern),
              getPattern
            )
          ],
          [R.contains('replaceDotToComa'), R.always(R.replace('.', ',', value.toString()))],
          [R.T, R.always(value)]
        ])

        return getValue(format)
      }
    }
  })

export default i18n

pt-BR.json

{
  "global_currency": "R$",
  "global_currency_formatter": "$t(global_currency) {{value, currency|BRL}}",
  "global_date_formatter": "{{date, date|dd/MM/yyyy}}",
}