Next.js

export const revalidate = 60

const res = await fetch('https://api.example.com/posts', { next: { revalidate: 60 } })
const posts = await res.json()

export default function Page({ params }: { params: { id: string } }) {
  return <div>Post id: {params.id}</div>
}

const res = await fetch('https://example.com/api', {
  next: { revalidate: 60 },
})

'use client'

import { useRouter } from 'next/navigation'

export function GoButton() {
  const router = useRouter()
  return (
    <button onClick={() => router.push('/en')}>Go</button>
  )
}

import { cookies, headers } from 'next/headers'

export default function Page() {
  const cookieStore = cookies()
  const theme = cookieStore.get('theme')?.value
  const ua = headers().get('user-agent')
  return <div>{theme} {ua}</div>
}

export async function GET() {
  return Response.json({ ok: true })
}