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 controlled 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 a valid HTTP header name, this method throws a
TypeError
.
Returns
A boolean value.
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 |
---|
Fetch Standard # ref-for-dom-headers-has① |
Browser compatibility
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