INNER CODE UNIT · TypeScript

detectFromRootParams

i18next/next-i18next · src/appRouter/server.ts:171

async function detectFromRootParams(config: NormalizedConfig): Promise<string | undefined> {
  try {
    const rootParams: Record<string, (() => Promise<unknown>) | undefined> = await import('next/root-params')
    const value = await rootParams[config.localeParamName]?.()
    if (typeof value !== 'string') return undefined
    return findSupportedMatch(value, config.supportedLngs, config.nonExplicitSupportedLngs)
  } catch {
    return undefined
  }
}

// Per-request language detection, deduplicated within a single React render
const detectLanguage = cache(async (config: NormalizedConfig): Promise<string> => {
  const fromRoute = await detectFromRootParams(config)
  if (fromRoute) return fromRoute

  const headerList = await headers()
  const fromHeader = headerList.get(config.headerName)

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