Headers.has

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 controller by the user agent. These headers include the forbidden header names and forbidden response header names.

Syntax

myHeaders.has(name);

Parameters

name

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

Returns

A Boolean.

Example

Creating an empty Headers object is simple:

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

You could add a header to this using Headers.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

Specifications

Specification	Status	Comment
Fetch The definition of 'has()' in that specification.	Living Standard

Browser compatibility

See also

• ServiceWorker API
• HTTP access control (CORS)
• HTTP