Headers: get() method

BaselineWidely 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 inWeb Workers.

Theget() method of theHeaders interfacereturns a byte string of all the values of a header within aHeaders objectwith a given name. If the requested header doesn't exist in theHeadersobject, it returnsnull.

For security reasons, some headers can only be controlled by the user agent. Theseheaders include theforbidden request headersandforbidden response header names.

Syntax

get(name)

Parameters

name: The name of the HTTP header whose values you want to retrieve from theHeaders object. If the given name is not the name of an HTTP header, thismethod throws aTypeError. The name is case-insensitive.

Return value

AString sequence representing the values of the retrieved header ornull if this header is not set.

Examples

Creating an emptyHeaders object is simple:

const myHeaders = new Headers(); // Currently emptymyHeaders.get("Not-Set"); // Returns null

You could add a header to this usingHeaders.append, then retrieve itusingget():

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 allthe 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" ]