The Request()
constructor creates a new Request
object.
Request()
Syntax
new Request(input) new Request(input, init)
Parameters
- input
-
Defines the resource that you wish to fetch. This can either be:
- A
USVString
containing the direct URL of the resource you want to fetch. - A
Request
object, effectively creating a copy. Note the following behavioral updates to retain security while making the constructor less likely to throw exceptions:- If this object exists on another origin to the constructor call, the
Request.referrer
is stripped out. - If this object has a
Request.mode
ofnavigate
, themode
value is converted tosame-origin
.
- If this object exists on another origin to the constructor call, the
- A
- init Optional
-
An options object containing any custom settings that you want to apply to the request. The possible options are:
-
method
: The request method, e.g.,GET
,POST
. The default isGET
. -
headers
: Any headers you want to add to your request, contained within aHeaders
object or an object literal withString
values. -
body
: Any body that you want to add to your request: this can be aBlob
,BufferSource
,FormData
,URLSearchParams
,USVString
, orReadableStream
object. Note that a request using theGET
orHEAD
method cannot have a body. -
mode
: The mode you want to use for the request, e.g.,cors
,no-cors
,same-origin
, ornavigate
. The default iscors
. -
credentials
: The request credentials you want to use for the request:omit
,same-origin
, orinclude
. The default issame-origin
. -
cache
: The cache mode you want to use for the request. -
redirect
: The redirect mode to use:follow
,error
, ormanual
. The default isfollow
. -
referrer
: AUSVString
specifyingno-referrer
,client
, or a URL. The default isabout:client
. -
integrity
: Contains the subresource integrity value of the request (e.g.,sha256-BpfBw7ivV8q2jLiT13fxDYAe2tJllusRSZ273h2nFSE=
).
If you construct a new
Request
from an existingRequest
, any options you set in the init object for the new request replace any corresponding options set in the originalRequest
. For example:const oldRequest = new Request('https://github.com/mdn/content/issues/12959', { headers: { 'From': '[email protected]'}}); oldRequest.headers.get("From"); // "[email protected]" const newRequest = new Request(oldRequest, { headers: { 'From': '[email protected]'}}); newRequest.headers.get('From') // "[email protected]"
-
Errors
Type | Description |
---|---|
TypeError |
Since Firefox 43, Request() will throw a TypeError if the URL has credentials, such as http://user:[email protected]. |
Examples
In our Fetch Request example (see Fetch Request live) we create a new Request
object using the constructor, then fetch it using a fetch()
call. Since we are fetching an image, we run Response.blob
on the response to give it the proper MIME type so it will be handled properly, then create an Object URL of it and display it in an <img>
element.
var myImage = document.querySelector('img'); var myRequest = new Request('flowers.jpg'); fetch(myRequest).then(function(response) { return response.blob(); }).then(function(response) { var objectURL = URL.createObjectURL(response); myImage.src = objectURL; });
In our Fetch Request with init example (see Fetch Request init live) we do the same thing except that we pass in an init object when we invoke fetch()
:
var myImage = document.querySelector('img'); var myHeaders = new Headers(); myHeaders.append('Content-Type', 'image/jpeg'); var myInit = { method: 'GET', headers: myHeaders, mode: 'cors', cache: 'default' }; var myRequest = new Request('flowers.jpg',myInit); fetch(myRequest).then(function(response) { ... });
Note that you could also pass the init object into the fetch
call to get the same effect, e.g.:
fetch(myRequest,myInit).then(function(response) { ... });
You can also use an object literal as headers
in init
.
var myInit = { method: 'GET', headers: { 'Content-Type': 'image/jpeg' }, mode: 'cors', cache: 'default' }; var myRequest = new Request('flowers.jpg', myInit);
You may also pass a Request
object to the Request()
constructor to create a copy of the Request (This is similar to calling the clone()
method.)
var copy = new Request(myRequest);
Note: This last usage is probably only useful in ServiceWorkers.
Specifications
Specification |
---|
Fetch Standard # ref-for-dom-request① |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
Request |
40
From Chrome 47, default values for the
init argument's properties changed.
mode defaults to
same-origin (from
no-cors ).
credentials defaults to
include (from
same-origin ).
redirect defaults to
follow (from
manual ).
|
14
|
39
|
No
|
27
|
10.1
|
40
From WebView 47, default values for the
init argument's properties changed.
mode defaults to
same-origin (from
no-cors ).
credentials defaults to
include (from
same-origin ).
redirect defaults to
follow (from
manual ).
|
40
From Chrome 47, default values for the
init argument's properties changed.
mode defaults to
same-origin (from
no-cors ).
credentials defaults to
include (from
same-origin ).
redirect defaults to
follow (from
manual ).
|
39
|
27
|
10.3
|
5.0
Some default values for the init parameter changed in Samsung Internet 5.0. See the Properties section for details.
4.0
|
cross_origin_stripped |
69
|
15
|
54
|
No
|
56
|
10.1
|
69
|
69
|
54
|
48
|
10.3
|
10.0
|
init_referrer_parameter |
47
|
15
|
47
|
No
|
34
|
10.1
|
47
|
47
|
47
|
34
|
10.3
|
5.0
|
navigate_mode |
49
|
15
|
46
|
No
|
36
|
10.1
|
No
|
49
|
46
|
No
|
10.3
|
5.0
|
readablestream_request_body |
No
|
No
|
No
|
No
|
No
|
No
|
No
|
No
|
No
|
No
|
No
|
No
|
reponse_body_readablestream |
43
|
≤79
|
65
|
No
|
30
|
No
|
43
|
43
|
65
|
No
|
10.3
|
4.0
|
See also
© 2005–2021 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/Request/Request