L422Y/Mass cancel Amazon Subscribe and Save.md

await Promise.all([...document.querySelectorAll('[data-subscription-id]')]
  .map(el => el.getAttribute('data-subscription-id'))
  .map(async (subscriptionId) => {
    try {
      const res = await fetch(`https://www.amazon.com/auto-deliveries/ajax/cancelSubscription?deviceType=desktop&deviceContext=web&subscriptionId=${subscriptionId}`)
      const cancelPanel = await res.text()

      const div = document.createElement('div')
      div.innerHTML = cancelPanel
      document.body.appendChild(div)

      const form = div.querySelector("form[name='cancelForm']")
      if (form) {
        const formData = new FormData(form)
        const formEntries = Object.fromEntries(formData.entries())

        await fetch(form.action, {
          method: form.method,
          headers: {
            'Content-Type': 'application/x-www-form-urlencoded',
          },
          body: new URLSearchParams(formEntries)
        })

        div.remove()
      }

      return 'ok'
    } catch (reason) {
      return `error: ${reason}`
    }
  })
)