This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for the proper prefixes to use in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the spec changes.

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


var myHeaders = request.headers;


A Headers object.


In the following snippet, we create a new request using the Request.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'


Specification Status Comment
The definition of 'headers' in that specification.
Living Standard Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 42
39 (39)
Not supported


Not supported
Feature Android Firefox Mobile (Gecko) Firefox OS (Gecko) IE Phone Opera Mobile Safari Mobile Chrome for Android
Basic support Not supported Not supported Not supported Not supported Not supported Not supported Not supported

[1] This feature is implemented behind a preference.

See also

Document Tags and Contributors

 Contributors to this page: Sebastianz, chrisdavidmills, kscarfone
 Last updated by: Sebastianz,