Headers.get()
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.
Syntax
myHeaders.get(name);
Parameters
name
-
The name of the HTTP header whose values you want to retrieve from the
Headers
object. If the given name is not the name of an HTTP header, this method throws aTypeError
. The name is case-insensitive.
Returns
A String
sequence representing the values of the retrieved header or
null
if this header is not set.
Example
Creating an empty Headers
object is simple:
var myHeaders = new Headers(); // Currently empty
myHeaders.get('Not-Set'); // Returns null
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"
myHeaders.get('Accept-Encoding').split(',').map(v => v.trimStart()); // Returns [ "deflate", "gzip" ]
Specifications
Specification |
---|
Fetch Standard # ref-for-dom-headers-get① |
Browser compatibility
BCD tables only load in the browser