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.
myHeaders.has(name);
TypeError
.
A Boolean
.
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
Specification | Status | Comment |
---|---|---|
Fetch The definition of 'has()' in that specification. | Living Standard |
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|---|
Basic support | 42 41 behind pref | (Yes) |
39 (39) 34 behind pref | No support | 29 | No support |
Feature | Android | Edge | Firefox Mobile (Gecko) | Firefox OS (Gecko) | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|---|
Basic support | No support | (Yes) | No support | No support | No support | No support | No support | No support |
© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/Headers/has