Using fetch API

fetch.js

// GET:
// no custom headers
fetch(url)
  .then(response => response.json())
  .then(data => {
      console.log(data) 
   })
.catch(error => console.error(error))

// custom headers:
fetch(url', {
  headers: new Headers({
    'User-agent': 'Mozilla/4.0 Custom User Agent'
  })
})
 .then(response => response.json())
 .then(data => {
     console.log(data)
  })
    .catch(error => console.error(error))

// CORS
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Credentials
fetch('https://api.github.com/orgs/nodejs', {
  credentials: 'include', // Useful for including session ID (and, IIRC, authorization headers)
})
 .then(response => response.json())
 .then(data => {
     console.log(data) // Prints result from `response.json()`
})
 .catch(error => console.error(error))

// POST:
// JSON
postRequest('http://example.com/api/v1/users', {user: 'Tom'})
  .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))
}

// Form (encoded) data:
postFormData('http://example.com/api/v1/users', {user: 'Tom'})
  .then(data => console.log(data))

function postFormData(url, data) {
  return fetch(url, {
    method: 'POST', // 'GET', 'PUT', 'DELETE', etc.
    body: new URLSearchParams(data),
    headers: new Headers({
      'Content-type': 'application/x-www-form-urlencoded; charset=UTF-8'
    })
  })
  .then(response => response.json())
  .catch(error => console.error(error))
}