Function createIntl

packages/intl/create-intl.ts:57–162

(
  config: IntlConfig<T>,
  cache?: IntlCache
)

 * @param cache cache for formatter instances to prevent memory leak
 */
export function createIntl<T = string>(
  config: IntlConfig<T>,
  cache?: IntlCache
): IntlShape<T> {
  const formatters = createFormatters(cache)
  const resolvedConfig: ResolvedIntlConfig<T> = {
    ...DEFAULT_INTL_CONFIG,
    ...config,
  }

  const {locale, defaultLocale, onError} = resolvedConfig
  if (!locale) {
    if (onError) {
      onError(
        new InvalidConfigError(
          `"locale" was not configured, using "${defaultLocale}" as fallback. See https://formatjs.github.io/docs/react-intl/api#intlshape for more details`
        )
      )
    }
    // Since there's no registered locale data for `locale`, this will
    // fallback to the `defaultLocale` to make sure things can render.
    // The `messages` are overridden to the `defaultProps` empty object
    // to maintain referential equality across re-renders. It's assumed
    // each <FormattedMessage> contains a `defaultMessage` prop.
    resolvedConfig.locale = resolvedConfig.defaultLocale || 'en'
  } else if (!Intl.NumberFormat.supportedLocalesOf(locale).length && onError) {
    onError(
      new MissingDataError(
        `Missing locale data for locale: "${locale}" in Intl.NumberFormat. Using default locale: "${defaultLocale}" as fallback. See https://formatjs.github.io/docs/react-intl#runtime-requirements for more details`
      )
    )
  } else if (
    !Intl.DateTimeFormat.supportedLocalesOf(locale).length &&
    onError
  ) {
    onError(
      new MissingDataError(
        `Missing locale data for locale: "${locale}" in Intl.DateTimeFormat. Using default locale: "${defaultLocale}" as fallback. See https://formatjs.github.io/docs/react-intl#runtime-requirements for more details`
      )
    )
  }

  verifyConfigMessages(resolvedConfig)
  return {
    ...resolvedConfig,
    formatters,
    formatNumber: formatNumber.bind(
      null,
      resolvedConfig,
      formatters.getNumberFormat
    ),
    formatNumberToParts: formatNumberToParts.bind(
      null,
      resolvedConfig,
      formatters.getNumberFormat
    ),
    formatRelativeTime: formatRelativeTime.bind(
      null,