web api instance method
Headers: get() method
Available in 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
name- : The name of the HTTP header whose values you want to retrieve from the
Headersobject. If the given name doesn’t match the field-name production in the HTTP specification, this method throws aTypeError. The name is case-insensitive.
- : The name of the HTTP header whose values you want to retrieve from the
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 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" ]