Client side code that uses fetch API to submit a form

submitMessage.js

function submitMessage(e) {
  e.preventDefault();

  let name = document.getElementById('name').value;
  fetch('<YOUR FUNCTION URL GOES HERE>', {
      method: 'POST',
      headers: {
        'Accept': 'application/json, text/plain, */*',
        'Content-type': 'application/json'
      },
      body: JSON.stringify({
        name: name
      })
    })
    .then((res) => processResponse(res))
}