This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage 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 specification changes.
The get()
method of the Headers
interface returns a byte string of all the values of a header within a Headers
object with a given name. If the requested header doesn't exist in the Headers
object, it returns null
.
For security reasons, some headers can only be controlled by the user agent. These headers include the forbidden header names and forbidden response header names.
myHeaders.get(name);
Headers
object. If the given name is not the name of an HTTP header, this method throws a TypeError
.
A ByteString
sequence representing the values of the retrieved header.
Creating an empty Headers
object is simple:
var myHeaders = new Headers(); // Currently empty
You could add a header to this using Headers.append
, then retrieve it using get()
:
myHeaders.append('Content-Type', 'image/jpeg'); myHeaders.get('Content-Type'); // Returns "image/jpeg"
If the header has multiple values associated with it, the byte string will contain all the values, in the order they were added to the Headers object:
myHeaders.append('Accept-Encoding', 'deflate'); myHeaders.append('Accept-Encoding', 'gzip'); myHeaders.get('Accept-Encoding'); // Returns "deflate,gzip"
Note: Headers.getAll
used to have this functionality, with Headers.get
returning only the first value added to the Headers
object. The latest spec has removed getAll()
, and updated get()
to return all values.
Specification | Status | Comment |
---|---|---|
Fetch The definition of 'get()' in that specification. | Living Standard |
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 42 41 behind pref |
39 (39) 34 behind pref 52 (52)[1] | No support | 29 | No support |
Feature | Android | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|
Basic support | ? | (Yes) | No support | ? | No support | ? |
[1] Prior to Firefox 52, get()
only returned the first value in the specified header, with getAll()
returning all values. From 52 onwards, get()
now returns all values and getAll()
has been deleted.
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/Headers/get