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 request headers 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 # ref-for-dom-headers-get① |
Browser compatibility
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