index.js

const proxyurl = 'https://cors-anywhere.herokuapp.com/'

const url =
  'https://cors-anywhere.herokuapp.com/https://us-central1-otp-react-native-4e01f.cloudfunctions.net/Mailer'
const submitbtn = document.querySelector('.submit-btn')
submitbtn.addEventListener('click', async event => {
  event.preventDefault()
  const fullname = document.querySelector('.fullname').value
  const email = document.querySelector('.email').value
  const message = document.getElementById('message').value
  if (!fullname || !email || !message) {
    return alert('fields cannot be empty')
  }
  submitbtn.textContent = 'Sending mail...'
  try {
    const mail = await axios.post(url, {
      subject: fullname,
      from: email,
      message
    })
    submitbtn.textContent = 'Mail Sent'
    document.querySelector('.fullname').value = ''
    document.querySelector('.email').value = ''
    document.getElementById('message').value = ''
    submitbtn.disabled = true

    console.log(mail)
  } catch (err) {
    console.log(err)
    submitbtn.textContent = 'Failed to send the mail'
  }
})