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.
* Some parts of this feature may have varying levels of support.
Note: This feature is available in Web Workers.
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
Requestobject.
Instance properties
Request.bodyRead only-
A
ReadableStreamof the body contents. Request.bodyUsedRead only-
Stores
trueorfalseto indicate whether or not the body has been used in a request yet. Request.cacheRead only-
Contains the cache mode of the request (e.g.,
default,reload,no-cache). Request.credentialsRead only-
Contains a value controlling whether credentials should be included with the request (e.g.,
omit,same-origin,include). The default issame-origin. Request.destinationRead only-
A string describing the type of content being requested.
Request.duplexRead only Experimental-
The duplex mode of the request, which determines whether the browser must send the entire request before processing the response.
Request.headersRead only-
Contains the associated
Headersobject of the request. Request.integrityRead only-
Contains the subresource integrity value of the request (e.g.,
sha256-BpfBw7ivV8q2jLiT13fxDYAe2tJllusRSZ273h2nFSE=). -
A boolean indicating whether the request is a history navigation.
Request.keepaliveRead only-
Contains the request's
keepalivesetting (trueorfalse), which indicates whether the browser will keep the associated request alive if the page that initiated it is unloaded before the request is complete. Request.methodRead only-
Contains the request's method (
GET,POST, etc.) Request.modeRead only-
Contains the mode of the request (e.g.,
cors,no-cors,same-origin,navigate.) Request.redirectRead only-
Contains the mode for how redirects are handled. It may be one of
follow,error, ormanual. Request.referrerRead only-
Contains the referrer of the request (e.g.,
client). Request.referrerPolicyRead only-
Contains the referrer policy of the request (e.g.,
no-referrer). Request.signalRead only-
Returns the
AbortSignalassociated with the request Request.urlRead only-
Contains the URL of the request.
Instance methods
Request.arrayBuffer()-
Returns a promise that resolves with an
ArrayBufferrepresentation of the request body. Request.blob()-
Returns a promise that resolves with a
Blobrepresentation of the request body. Request.bytes()-
Returns a promise that resolves with a
Uint8Arrayrepresentation of the request body. Request.clone()-
Creates a copy of the current
Requestobject. Request.formData()-
Returns a promise that resolves with a
FormDatarepresentation 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 needs 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) {
throw new Error("Something went wrong on API server!");
}
return response.json();
})
.then((response) => {
console.debug(response);
// …
})
.catch((error) => {
console.error(error);
});
Specifications
| Specification |
|---|
| Fetch> # request-class> |
Browser compatibility
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