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:

const myRequest = new Request('flowers.jpg');
const 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:

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

const myInit = {
  method: 'GET',
  headers: myHeaders,
  mode: 'cors',
  cache: 'default'

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

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


Fetch Standard
# ref-for-dom-request-headers②

Browser compatibility

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See also