Fetch API & Handling JSON Responses

fetch('/api/data', {
  credentials: 'include',
  headers: {
    'Authorization': 'Bearer ' + token
  }
})

To send login credentials
To include cookies in cross-origin requests
The credentials option controls cookie behavior: 1) 'include' sends cookies even for cross-origin requests, 2) Essential for maintaining session state across domains, 3) Required for authenticated cross-origin requests, 4) Affects CORS policy requirements on server, 5) Default is 'same-origin' which only sends cookies to same domain, 6) Critical for secure cross-origin authentication.
To encrypt the request
To validate user permissions