What fetch options are commonly used for sending requests?

The most common fetch options are method, headers, body, and credentials.

fetch(url, {
  // HTTP method
  method: 'POST',
  // Request headers
  headers: { ... },
  // Request body (string or FormData)
  body: '...',
  // Send cookies cross-origin
  credentials: 'include'
});

Other options: mode (cors/no-cors), cache, redirect.