i18n

Build a Next.js App Router locale switcher that preserves the current path with usePathname and a regex swap, plus an accessible active state.

TL;DR: A naive locale switcher sent users to the locale homepage instead of the same page. The fix: a small client component that swaps the /en or /id prefix while preserving the rest of the pathname, plus aria-current for the active state. Stick with this for simple sites; adopt next-intl once routing grows complex.

The /en page kept showing Indonesian content while the build stayed green: synchronous page components that ignore params. The fix is obvious once you see it.

TL;DR: The /en pages rendered Indonesian because four page components were synchronous and returned hardcoded locale content, so they never touched params at all. The fix: make each page async, await params, map locales to content, and guard unknown locales with hasLocale plus a 404. Green builds only prove components render, not that locale content is correct.