Request
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since March 2017.
The Request
interface of the Fetch API represents a resource request.
You can create a new Request
object using the Request()
constructor, but you are more likely to encounter a Request
object being returned as the result of another API operation, such as a service worker FetchEvent.request
.
Constructor
Request()
-
Creates a new
Request
object.
Instance properties
Request.body
Read only-
A
ReadableStream
of the body contents. Request.bodyUsed
Read only-
Stores
true
orfalse
to indicate whether or not the body has been used in a request yet. Request.cache
Read only-
Contains the cache mode of the request (e.g.,
default
,reload
,no-cache
). Request.credentials
Read only-
Contains the credentials of the request (e.g.,
omit
,same-origin
,include
). The default issame-origin
. Request.destination
Read only-
A string describing the type of content being requested.
Request.headers
Read only-
Contains the associated
Headers
object of the request. Request.integrity
Read only-
Contains the subresource integrity value of the request (e.g.,
sha256-BpfBw7ivV8q2jLiT13fxDYAe2tJllusRSZ273h2nFSE=
). Request.method
Read only-
Contains the request's method (
GET
,POST
, etc.) Request.mode
Read only-
Contains the mode of the request (e.g.,
cors
,no-cors
,same-origin
,navigate
.) Request.redirect
Read only-
Contains the mode for how redirects are handled. It may be one of
follow
,error
, ormanual
. Request.referrer
Read only-
Contains the referrer of the request (e.g.,
client
). Request.referrerPolicy
Read only-
Contains the referrer policy of the request (e.g.,
no-referrer
). Request.signal
Read only-
Returns the
AbortSignal
associated with the request Request.url
Read only-
Contains the URL of the request.
Instance methods
Request.arrayBuffer()
-
Returns a promise that resolves with an
ArrayBuffer
representation of the request body. Request.blob()
-
Returns a promise that resolves with a
Blob
representation of the request body. Request.bytes()
-
Returns a promise that resolves with a
Uint8Array
representation of the request body. Request.clone()
-
Creates a copy of the current
Request
object. Request.formData()
-
Returns a promise that resolves with a
FormData
representation of the request body. Request.json()
-
Returns a promise that resolves with the result of parsing the request body as
JSON
. Request.text()
-
Returns a promise that resolves with a text representation of the request body.
Note: The request body functions can be run only once; subsequent calls will reject with TypeError showing that the body stream has already used.
Examples
In the following snippet, we create a new request using the Request()
constructor (for an image file in the same directory as the script), then return some property values of the request:
const request = new Request("https://www.mozilla.org/favicon.ico");
const url = request.url;
const method = request.method;
const credentials = request.credentials;
You could then fetch this request by passing the Request
object in as a parameter to a fetch()
call, for example:
fetch(request)
.then((response) => response.blob())
.then((blob) => {
image.src = URL.createObjectURL(blob);
});
In the following snippet, we create a new request using the Request()
constructor with some initial data and body content for an API request which need a body payload:
const request = new Request("https://example.com", {
method: "POST",
body: '{"foo": "bar"}',
});
const url = request.url;
const method = request.method;
const credentials = request.credentials;
const bodyUsed = request.bodyUsed;
Note: The body can only be a Blob
, an ArrayBuffer
, a TypedArray
, a DataView
, a FormData
, a URLSearchParams
, a ReadableStream
, or a String
object, as well as a string literal, so for adding a JSON object to the payload you need to stringify that object.
You could then fetch this API request by passing the Request
object in as a parameter to a fetch()
call, for example and get the response:
fetch(request)
.then((response) => {
if (response.status === 200) {
return response.json();
} else {
throw new Error("Something went wrong on API server!");
}
})
.then((response) => {
console.debug(response);
// …
})
.catch((error) => {
console.error(error);
});
Specifications
Specification |
---|
Fetch Standard # request-class |
Browser compatibility
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