Request.headers

The headers read-only property of the Request interface contains the Headers object associated with the request.

A Headers object.

In the following snippet, we create a new request using the Request() constructor (for an image file in the same directory as the script), then save the request headers in a variable:

var myRequest = new Request('flowers.jpg');
var myHeaders = myRequest.headers; // Headers {}

To add a header to the Headers object we use Headers.append; we then create a new Request along with a 2nd init parameter, passing headers in as an init option:

var myHeaders = new Headers();
myHeaders.append('Content-Type', 'image/jpeg');

var myInit = {
  method: 'GET',
  headers: myHeaders,
  mode: 'cors',
  cache: 'default'
};

var myRequest = new Request('flowers.jpg', myInit);

myContentType = myRequest.headers.get('Content-Type'); // returns 'image/jpeg'

• ServiceWorker API
• HTTP access control (CORS)
• HTTP