web api instance method

Headers: has() method

Available in workers

The has() method of the Headers interface returns a boolean stating whether a Headers object contains a certain header.

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

has(name)

name
- : The name of the HTTP header you want to test for. If the given name is not a valid HTTP header name, this method throws a TypeError.

A boolean value.

Creating an empty Headers object is simple:

const myHeaders = new Headers(); // Currently empty

You could add a header to this using append, then test for the existence of it using has():

myHeaders.append("Content-Type", "image/jpeg");
myHeaders.has("Content-Type"); // Returns true
myHeaders.has("Accept-Encoding"); // Returns false

SpecificationsStandards references are available on the canonical MDN page.

Browser compatibilityCompatibility data is available on the canonical MDN page.