fetch examples: https://danlevy.net/you-may-not-need-axios/

posting-json.js

postRequest('http://example.com/api/v1/users', {user: 'Dan'})
  .then(data => console.log(data)) // Result from the `response.json()` call

function postRequest(url, data) {
  return fetch(url, {
    credentials: 'same-origin', // 'include', default: 'omit'
    method: 'POST',             // 'GET', 'PUT', 'DELETE', etc.
    body: JSON.stringify(data), // Use correct payload (matching 'Content-Type')
    headers: { 'Content-Type': 'application/json' },
  })
  .then(response => response.json())
  .catch(error => console.error(error))
}