nextjs-router-source-example-11.tsx

// packages/next/client/index.ts

// Router 싱글톤을 저장하는 전역 객체
// https://github.com/vercel/next.js/blob/v12.3.4/packages/next/client/index.tsx#L67
export let router: Router

// AppContainer에서 RouterContext에 Router 싱글톤 주입하는 코드
// https://github.com/vercel/next.js/blob/v12.3.4/packages/next/client/index.tsx#L296
function AppContainer({
  children,
}: React.PropsWithChildren<{}>): React.ReactElement {
  return (
    <Container>
      <RouterContext.Provider value={makePublicRouterInstance(router)}>
        {/* ... */}
      </RouterContext.Provider>
    </Container>
  )
}