The Headers()
constructor creates a new Headers
object.
Syntax
var myHeaders = new Headers(init);
Parameters
init
Optional- An object containing any HTTP headers that you want to pre-populate your
Headers
object with. This can be a simple object literal withByteString
values; or an existingHeaders
object. In the last case, the newHeaders
object inherits its data from the existingHeaders
object.
Example
Creating an empty Headers
object is simple:
var myHeaders = new Headers(); // Currently empty
You could add a header to this using Headers.append
:
myHeaders.append('Content-Type', 'image/jpeg'); myHeaders.get('Content-Type'); // Returns 'image/jpeg'
Or you can add the headers you want as the Headers
object is created. In the following snippet we create a new Headers
object, adding some headers by passing the constructor an init object as an argument:
var httpHeaders = { 'Content-Type' : 'image/jpeg', 'Accept-Charset' : 'utf-8', 'X-My-Custom-Header' : 'Zeke are cool' }; var myHeaders = new Headers(httpHeaders);
You can now create another Headers
object, passing it the first Headers
object as its init object:
var secondHeadersObj = new Headers(myHeaders); secondHeadersObj.get('Content-Type'); // Would return 'image/jpeg' — it inherits it from the first headers object
Specifications
Specification | Status | Comment |
---|---|---|
Fetch The definition of 'Headers()' in that specification. |
Living Standard |
Browser compatibility
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