next.js/packages/next/src/client/detect-domain-locale.ts

import type { detectDomainLocale as Fn } from '../shared/lib/i18n/detect-domain-locale'

export const detectDomainLocale: typeof Fn = (...args) => {
  if (process.env.__NEXT_I18N_SUPPORT) {
    return (
      require('../shared/lib/i18n/detect-domain-locale') as typeof import('../shared/lib/i18n/detect-domain-locale')
    ).detectDomainLocale(...args)
  }
}