Drill 15: Find the core line — Forms without a reload

form.addEventListener('submit', async (event) => {
  event.preventDefault()
  const button = form.querySelector('button')
  button.disabled = true
  try {
    const response = await fetch('/api/signup', { method: 'POST', body: new FormData(form) })
    if (!response.ok) throw new Error('Save failed')
  } finally {
    button.disabled = false
  }
})