The headers
read-only property of the Request
interface contains the Headers
object associated with the request.
Syntax
var myHeaders = request.headers;
Value
A Headers
object.
Example
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'
Specifications
Specification | Status | Comment |
---|---|---|
Fetch The definition of 'headers' in that specification. |
Living Standard | Initial definition |
Browser compatibility
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|---|
Basic support | 42 41[1] |
(Yes) | 39 (39) 34[1] |
No support |
29 |
No support |
Feature | Android | Edge | Firefox Mobile (Gecko) | Firefox OS (Gecko) | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|---|
Basic support | No support | (Yes) | No support | No support | No support | No support | No support | No support |
[1] This feature is implemented behind a preference.