next.js/test/development/app-dir/source-mapping/app/form.tsx

'use client'

import { useActionState } from 'react'

export function Form({
  action,
  id,
}: {
  action: () => Promise<string>
  id: string
}) {
  const [result, formAction] = useActionState(action, 'initial')

  return (
    <form id={id} action={formAction}>
      <button>Submit</button>
      <p>{result}</p>
    </form>
  )
}