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Request()

The Request() constructor creates a new Request object.

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 of navigate, the mode value is converted to same-origin.
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 is GET.
  • headers: Any headers you want to add to your request, contained within a Headers object or an object literal with String values.
  • body: Any body that you want to add to your request: this can be a Blob, BufferSource, FormData, URLSearchParams, USVString, or ReadableStream object. Note that a request using the GET or HEAD method cannot have a body.
  • mode: The mode you want to use for the request, e.g., cors, no-cors, same-origin, or navigate. The default is cors.
  • credentials: The request credentials you want to use for the request: omit, same-origin, or include. The default is same-origin.
  • cache: The cache mode you want to use for the request.
  • redirect: The redirect mode to use: follow, error, or manual. The default is follow.
  • referrer: A USVString specifying no-referrer, client, or a URL. The default is about:client.
  • integrity: Contains the subresource integrity value of the request (e.g., sha256-BpfBw7ivV8q2jLiT13fxDYAe2tJllusRSZ273h2nFSE=).

If you construct a new Request from an existing Request, any options you set in the init object for the new request replace any corresponding options set in the original Request. 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

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