The get()
method of the Headers
interface returns a byte string of all the values of a header within a Headers
object with a given name. If the requested header doesn't exist in the Headers
object, it returns null
.
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.get(name);
Parameters
name
- The name of the HTTP header whose values you want to retrieve from the
Headers
object. If the given name is not the name of an HTTP header, this method throws aTypeError
. The name is case-insensitive.
Returns
A ByteString
sequence representing the values of the retrieved header or null
if this header is not set.
Example
Creating an empty Headers
object is simple:
var myHeaders = new Headers(); // Currently empty myHeaders.get('Not-Set'); // Returns null
You could add a header to this using Headers.append
, then retrieve it using get()
:
myHeaders.append('Content-Type', 'image/jpeg'); myHeaders.get('Content-Type'); // Returns "image/jpeg"
If the header has multiple values associated with it, the byte string will contain all the values, in the order they were added to the Headers object:
myHeaders.append('Accept-Encoding', 'deflate'); myHeaders.append('Accept-Encoding', 'gzip'); myHeaders.get('Accept-Encoding'); // Returns "deflate,gzip"
Note: Headers.getAll
used to have this functionality, with Headers.get
returning only the first value added to the Headers
object. The latest spec has removed getAll()
, and updated get()
to return all values.
Specifications
Specification | Status | Comment |
---|---|---|
Fetch The definition of 'get()' in that specification. |
Living Standard |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
get | Chrome
Full support
42
| Edge Full support 14 | Firefox
Full support
52
| IE No support No | Opera
Full support
29
| Safari Full support 10.1 | WebView Android Full support 42 | Chrome Android
Full support
42
| Firefox Android No support No | Opera Android
Full support
29
| Safari iOS No support No | Samsung Internet Android Full support 4.0 |
Legend
- Full support
- Full support
- No support
- No support
- Experimental. Expect behavior to change in the future.
- Experimental. Expect behavior to change in the future.
- See implementation notes.
- See implementation notes.
- User must explicitly enable this feature.
- User must explicitly enable this feature.