Headers: get() method
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since March 2017.
Note: This feature is available in Web Workers.
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
get(name)
Parameters
Return value
A String
sequence representing the values of the retrieved header or
null
if this header is not set.
Examples
Creating an empty Headers
object is simple:
const 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