Headers()
The Headers()
constructor creates a new Headers
object.
Syntax
var myHeaders = new Headers(init);
Parameters
-
init
Optional -
An object containing any HTTP headers that you want to pre-populate your
Headers
object with. This can be a simple object literal withString
values; or an existingHeaders
object. In the last case, the newHeaders
object copies its data from the existingHeaders
object.
Example
Creating an empty Headers
object is simple:
var myHeaders = new Headers(); // Currently empty
You could add a header to this using Headers.append
:
myHeaders.append('Content-Type', 'image/jpeg'); myHeaders.get('Content-Type'); // Returns 'image/jpeg'
Or you can add the headers you want as the Headers
object is created. In the following snippet we create a new Headers
object, adding some headers by passing the constructor an init object as an argument:
var httpHeaders = { 'Content-Type' : 'image/jpeg', 'X-My-Custom-Header' : 'Zeke are cool' }; var myHeaders = new Headers(httpHeaders);
You can now create another Headers
object, passing it the first Headers
object as its init object:
var secondHeadersObj = new Headers(myHeaders); secondHeadersObj.get('Content-Type'); // Would return 'image/jpeg' — it inherits it from the first headers object
Specifications
Specification |
---|
Fetch Standard (Fetch) # ref-for-dom-headers① |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
Headers |
42 |
14 |
39 |
No |
29 |
10.1 |
42 |
42 |
No |
29 |
10.3 |
4.0 |
See also
© 2005–2021 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/Headers/Headers