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 request headers 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 |
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| Fetch # ref-for-dom-headers-has① |