Headers: has() method
Baseline Widely 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 in Web 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 header names and forbidden response header names.
Syntax
js
has(name)
Parameters
Return value
A boolean value.
Examples
Creating an empty Headers
object is simple:
js
const myHeaders = new Headers(); // Currently empty
You could add a header to this using Headers.append
, then test for the
existence of it using has()
:
js
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
BCD tables only load in the browser