web/lib/src/dom/fetch.dart

// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
//
// API docs from [MDN Web Docs](https://developer.mozilla.org/en-US/docs/Web).
// Attributions and copyright licensing by Mozilla Contributors is licensed
// under [CC-BY-SA 2.5](https://creativecommons.org/licenses/by-sa/2.5/.

// Generated from Web IDL definitions.

// ignore_for_file: unintended_html_in_doc_comment

@JS()
library;

import 'dart:js_interop';

import 'attribution_reporting_api.dart';
import 'dom.dart';
import 'fileapi.dart';
import 'private_network_access.dart';
import 'referrer_policy.dart';
import 'streams.dart';
import 'trust_token_api.dart';
import 'xhr.dart';

typedef HeadersInit = JSObject;
typedef XMLHttpRequestBodyInit = JSAny;
typedef BodyInit = JSAny;
typedef RequestInfo = JSAny;
typedef RequestDestination = String;
typedef RequestMode = String;
typedef RequestCredentials = String;
typedef RequestCache = String;
typedef RequestRedirect = String;
typedef RequestDuplex = String;
typedef RequestPriority = String;
typedef ResponseType = String;

/// The **`Headers`** interface of the
/// [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API)
/// allows you to perform various actions on
/// [HTTP request and response headers](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers).
/// These actions include retrieving, setting, adding to, and removing headers
/// from the list of the request's headers.
///
/// You can retrieve a `Headers` object via the [Request.headers] and
/// [Response.headers] properties, and create a new `Headers` object using the
/// [Headers.Headers] constructor. Compared to using plain objects, using
/// `Headers` objects to send requests provides some additional input
/// sanitization. For example, it normalizes header names to lowercase, strips
/// leading and trailing whitespace from header values, and prevents certain
/// headers from being set.
///
/// > [!NOTE]
/// > You can find out more about the available headers by reading our
/// > [HTTP headers](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers)
/// > reference.
///
/// ---
///
/// API documentation sourced from
/// [MDN Web Docs](https://developer.mozilla.org/en-US/docs/Web/API/Headers).
extension type Headers._(JSObject _) implements JSObject {
  external factory Headers([HeadersInit init]);

  /// The **`append()`** method of the [Headers]
  /// interface appends a new value onto an existing header inside a `Headers`
  /// object, or adds the header if it does not already exist.
  ///
  /// The difference between [Headers.set] and `append()` is
  /// that if the specified header already exists and accepts multiple values,
  /// `set()` will overwrite the existing value with the new one, whereas
  /// `append()` will append the new value onto the end of the set of values.
  ///
  /// For security reasons, some headers can only be controlled by the user
  /// agent. These
  /// headers include the
  /// and .
  external void append(
    String name,
    String value,
  );

  /// The **`delete()`** method of the [Headers]
  /// interface deletes a header from the current `Headers` object.
  ///
  /// For security reasons, some headers can only be controlled by the user
  /// agent. These
  /// headers include the
  /// and .
  external void delete(String name);

  /// The **`get()`** method of the [Headers] interface
  /// returns a byte string of all the values of a header within a `Headers`
  /// object
  /// with a given name. If the requested header doesn't exist in the `Headers`
  /// object, it returns `null`.
  ///
  /// For security reasons, some headers can only be controlled by the user
  /// agent. These
  /// headers include the
  /// and .
  external String? get(String name);

  /// The **`getSetCookie()`** method of the [Headers] interface returns an
  /// array containing the values of all  headers associated with a response.
  /// This allows [Headers] objects to handle having multiple `Set-Cookie`
  /// headers, which wasn't possible prior to its implementation.
  ///
  /// This method is intended for use on server environments (for example
  /// Node.js). Browsers block frontend JavaScript code from accessing the
  /// header, as required by the Fetch spec, which defines `Set-Cookie` as a
  /// [forbidden response-header name](https://fetch.spec.whatwg.org/#forbidden-response-header-name)
  /// that
  /// [must be filtered out](https://fetch.spec.whatwg.org/#ref-for-forbidden-response-header-name%E2%91%A0)
  /// from any response exposed to frontend code.
  external JSArray<JSString> getSetCookie();

  /// The **`has()`** method of the [Headers] interface
  /// returns a boolean stating whether a `Headers` object contains a certain
  /// header.
  ///
  /// For security reasons, some headers can only be controlled by the user
  /// agent. These
  /// headers include the
  /// and .
  external bool has(String name);

  /// The **`set()`** method of the [Headers] interface
  /// sets a new value for an existing header inside a `Headers` object, or adds
  /// the header if it does not already exist.
  ///
  /// The difference between `set()` and [Headers.append] is that if
  /// the specified header already exists and accepts multiple values, `set()`
  /// overwrites the existing value with the new one, whereas [Headers.append]
  /// appends the new value to the end of the set of values.
  ///
  /// For security reasons, some headers can only be controlled by the user
  /// agent. These
  /// headers include the
  /// and .
  external void set(
    String name,
    String value,
  );
}

/// The **`Request`** interface of the
/// [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API)
/// represents a resource request.
///
/// You can create a new `Request` object using the [Request.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].
///
/// ---
///
/// API documentation sourced from
/// [MDN Web Docs](https://developer.mozilla.org/en-US/docs/Web/API/Request).
extension type Request._(JSObject _) implements JSObject {
  external factory Request(
    RequestInfo input, [
    RequestInit init,
  ]);

  /// The **`clone()`** method of the [Request] interface creates a copy of the
  /// current `Request` object.
  ///
  /// Like the underlying [ReadableStream.tee] api,
  /// the [Request.body] of a cloned `Response`
  /// will signal backpressure at the rate of the _faster_ consumer of the two
  /// bodies,
  /// and unread data is enqueued internally on the slower consumed `body`
  /// without any limit or backpressure.
  /// Beware when you construct a `Request` from a stream and then `clone` it.
  ///
  /// `clone()` throws a `TypeError` if the request body has already been used.
  /// In fact, the main reason `clone()` exists is to allow multiple uses of
  /// body objects (when they are one-use only.)
  ///
  /// If you intend to modify the request, you may prefer the [Request]
  /// constructor.
  external Request clone();

  /// The **`arrayBuffer()`** method of the [Request] interface
  /// reads the request body and returns it as a promise that resolves with an
  /// `ArrayBuffer`.
  external JSPromise<JSArrayBuffer> arrayBuffer();

  /// The **`blob()`** method of the [Request] interface
  /// reads the request body and returns it as a promise that resolves with a
  /// [Blob].
  external JSPromise<Blob> blob();

  /// The **`bytes()`** method of the [Request] interface reads the request body
  /// and returns it as a promise that resolves with an `Uint8Array`.
  external JSPromise<JSUint8Array> bytes();

  /// The **`formData()`** method of the [Request] interface
  /// reads the request body and returns it as a promise that resolves with a
  /// [FormData] object.
  external JSPromise<FormData> formData();

  /// The **`json()`** method of the [Request] interface
  /// reads the request body and returns it as a promise that resolves with the
  /// result of parsing the body text as `JSON`.
  ///
  /// Note that despite the method being named `json()`, the result is not JSON
  /// but is instead the result of taking JSON as input and parsing it to
  /// produce a JavaScript object.
  external JSPromise<JSAny?> json();

  /// The **`text()`** method of the [Request] interface
  /// reads the request body and returns it as a promise that resolves with a
  /// `String`.
  /// The response is _always_ decoded using UTF-8.
  external JSPromise<JSString> text();

  /// The **`method`** read-only property of the
  /// [Request] interface contains the request's method (`GET`,
  /// `POST`, etc.)
  external String get method;

  /// The **`url`** read-only property of the [Request]
  /// interface contains the URL of the request.
  external String get url;

  /// The **`headers`** read-only property of the
  /// [Request] interface contains the [Headers] object associated
  /// with the request.
  external Headers get headers;

  /// The **`destination`** read-only
  /// property of the **[Request]** interface returns a string
  /// describing the type of content being requested.
  ///
  /// The string must be one of the `audio`, `audioworklet`,
  /// `document`, `embed`, `fencedframe`, `font`, `frame`,
  /// `iframe`, `image`, `json`, `manifest`, `object`,
  /// `paintworklet`, `report`, `script`, `sharedworker`,
  /// `style`, `track`, `video`, `worker`
  /// or `xslt` strings, or the empty string, which is the default value.
  ///
  /// The `destination` is used by the  to, for example,
  /// help determine which set of rules to follow for CORS purposes, or how to
  /// navigate any
  /// complicated code paths that affect how specific types of request get
  /// handled.
  ///
  /// These destinations vary substantially in how they operate. Some are data
  /// receptacles,
  /// where the received data is stored for processing later. Others are
  /// script-based, in
  /// which case the received data is delivered to a script by calling it and
  /// passing the data
  /// along. Script-based destinations include `script` elements, as well as
  /// any of the [Worklet]-based destinations
  /// (including subclasses like [AudioWorklet]), and the
  /// [Worker]-based destinations, including [ServiceWorker]
  /// and [SharedWorker].
  external RequestDestination get destination;

  /// The **`referrer`** read-only property of the
  /// [Request] interface is set by the user agent to be the referrer of the
  /// Request. (e.g., `client`, `no-referrer`, or a URL.)
  ///
  /// > [!NOTE]
  /// > If `referrer`'s value is `no-referrer`,
  /// > it returns an empty string.
  external String get referrer;

  /// The **`referrerPolicy`** read-only property of the
  /// [Request] interface returns the referrer policy, which governs what
  /// referrer information, sent in the `Referer` header, should be included
  /// with the request.
  external ReferrerPolicy get referrerPolicy;

  /// The **`mode`** read-only property of the [Request]
  /// interface contains the mode of the request (e.g., `cors`,
  /// `no-cors`, `same-origin`, or `navigate`.) This is used
  /// to determine if cross-origin requests lead to valid responses, and which
  /// properties of the response are readable.
  ///
  /// To construct a request with a specific mode, pass the desired value as the
  /// [RequestInit] option to the [Request.Request] constructor.
  ///
  /// Note that setting particular modes, especially `no-cors`, places
  /// restrictions on the request methods and headers that may be used, and
  /// prevents JavaScript from accessing the response headers or body. See the
  /// documentation for [RequestInit] for more details.
  external RequestMode get mode;

  /// The **`credentials`** read-only property of the [Request] interface
  /// reflects the value given to the [Request.Request] constructor in the
  /// [`credentials`](https://developer.mozilla.org/en-US/docs/Web/API/RequestInit#credentials)
  /// option. It determines whether or not the browser sends credentials with
  /// the request, as well as whether any **`Set-Cookie`** response headers are
  /// respected.
  ///
  /// Credentials are cookies,  client certificates, or authentication headers
  /// containing a username and password.
  ///
  /// See
  /// [Including credentials](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch#including_credentials)
  /// for more details.
  external RequestCredentials get credentials;

  /// The **`cache`** read-only property of the [Request] interface contains the
  /// cache mode of the request. It controls how the request will interact with
  /// the browser's
  /// [HTTP cache](https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching).
  external RequestCache get cache;

  /// The **`redirect`** read-only property of the [Request] interface contains
  /// the mode for how redirects are handled.
  external RequestRedirect get redirect;

  /// The **`integrity`** read-only property of the [Request] interface contains
  /// the
  /// [subresource integrity](https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity)
  /// value of the request.
  external String get integrity;

  /// The **`keepalive`** read-only property of the [Request] interface contains
  /// the request's `keepalive` setting (`true` or `false`), which indicates
  /// whether the browser will keep the associated request alive if the page
  /// that initiated it is unloaded before the request is complete.
  ///
  /// This enables a [Window.fetch] request to, for example, send analytics at
  /// the end of a session even if the user navigates away from or closes the
  /// page.
  /// This has some advantages over using [Navigator.sendBeacon] for the same
  /// purpose, including allowing you to use HTTP methods other than
  /// [`POST`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/POST),
  /// customize request properties, and access the server response via the fetch
  /// `Promise` fulfillment.
  /// It is also available in
  /// [service workers](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API).
  external bool get keepalive;

  /// The **`isHistoryNavigation`** read-only property of the [Request]
  /// interface is a boolean indicating whether the request is a history
  /// navigation.
  ///
  /// A history navigation is a navigation within the browser's history, made by
  /// calling [History.go], [History.back], [History.forward],
  /// [Navigation.traverseTo], [Navigation.back], [Navigation.forward], or
  /// directly by clicking the browser's back or forward navigation button.
  external bool get isHistoryNavigation;

  /// The read-only **`signal`** property of the [Request] interface returns the
  /// [AbortSignal] associated with the request.
  external AbortSignal get signal;

  /// The **`body`** read-only property of the [Request]
  /// interface contains a [ReadableStream] with the body contents
  /// that have been added to the request. Note that a request using the
  /// `GET` or `HEAD` method cannot have a body
  /// and `null` is returned in these cases.
  external ReadableStream? get body;

  /// The **`bodyUsed`** read-only property of the
  /// [Request] interface is a boolean value that indicates
  /// whether the request body has been read yet.
  external bool get bodyUsed;
}

/// The **`RequestInit`** dictionary of the
/// [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API)
/// represents the set of options that can be used to configure a
/// [fetch request](https://developer.mozilla.org/en-US/docs/Web/API/Window/fetch).
///
/// You can pass a `RequestInit` object into the [Request.Request] constructor,
/// or directly into the
/// [`fetch()`](https://developer.mozilla.org/en-US/docs/Web/API/Window/fetch)
/// function call.
///
/// You can also construct a `Request` with a `RequestInit`, and pass the
/// `Request` to a `fetch()` call along with another `RequestInit`. If you do
/// this, and the same option is set in both places, then the value passed
/// directly into `fetch()` is used.
///
/// ---
///
/// API documentation sourced from
/// [MDN Web Docs](https://developer.mozilla.org/en-US/docs/Web/API/RequestInit).
extension type RequestInit._(JSObject _) implements JSObject {
  external factory RequestInit({
    String method,
    HeadersInit headers,
    BodyInit? body,
    String referrer,
    ReferrerPolicy referrerPolicy,
    RequestMode mode,
    RequestCredentials credentials,
    RequestCache cache,
    RequestRedirect redirect,
    String integrity,
    bool keepalive,
    AbortSignal? signal,
    RequestDuplex duplex,
    RequestPriority priority,
    JSAny? window,
    AttributionReportingRequestOptions attributionReporting,
    IPAddressSpace targetAddressSpace,
    bool sharedStorageWritable,
    PrivateToken privateToken,
    bool adAuctionHeaders,
  });

  external String get method;
  external set method(String value);
  external HeadersInit get headers;
  external set headers(HeadersInit value);
  external BodyInit? get body;
  external set body(BodyInit? value);
  external String get referrer;
  external set referrer(String value);
  external ReferrerPolicy get referrerPolicy;
  external set referrerPolicy(ReferrerPolicy value);
  external RequestMode get mode;
  external set mode(RequestMode value);
  external RequestCredentials get credentials;
  external set credentials(RequestCredentials value);
  external RequestCache get cache;
  external set cache(RequestCache value);
  external RequestRedirect get redirect;
  external set redirect(RequestRedirect value);
  external String get integrity;
  external set integrity(String value);
  external bool get keepalive;
  external set keepalive(bool value);
  external AbortSignal? get signal;
  external set signal(AbortSignal? value);
  external RequestDuplex get duplex;
  external set duplex(RequestDuplex value);
  external RequestPriority get priority;
  external set priority(RequestPriority value);
  external JSAny? get window;
  external set window(JSAny? value);
  external AttributionReportingRequestOptions get attributionReporting;
  external set attributionReporting(AttributionReportingRequestOptions value);
  external IPAddressSpace get targetAddressSpace;
  external set targetAddressSpace(IPAddressSpace value);
  external bool get sharedStorageWritable;
  external set sharedStorageWritable(bool value);
  external PrivateToken get privateToken;
  external set privateToken(PrivateToken value);
  external bool get adAuctionHeaders;
  external set adAuctionHeaders(bool value);
}

/// The **`Response`** interface of the
/// [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API)
/// represents the response to a request.
///
/// You can create a new `Response` object using the [Response.Response]
/// constructor, but you are more likely to encounter a `Response` object being
/// returned as the result of another API operation—for example, a service
/// worker [FetchEvent.respondWith], or a simple [Window.fetch].
///
/// ---
///
/// API documentation sourced from
/// [MDN Web Docs](https://developer.mozilla.org/en-US/docs/Web/API/Response).
extension type Response._(JSObject _) implements JSObject {
  external factory Response([
    BodyInit? body,
    ResponseInit init,
  ]);

  /// The **`error()`** static method of the [Response] interface returns a new
  /// `Response` object associated with a network error.
  ///
  /// This is mainly useful when writing service workers: it enables a service
  /// worker to send a response from a [ServiceWorkerGlobalScope.fetch_event]
  /// event handler that will cause the [Window.fetch] call in the main app code
  /// to reject the promise.
  ///
  /// An error response has its [Response.type] set to `error`.
  external static Response error();

  /// The **`redirect()`** static method of the [Response] interface returns a
  /// `Response` resulting in a redirect to the specified URL.
  ///
  /// > [!NOTE]
  /// > This can be used alongside the
  /// > [ServiceWorker API](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API).
  /// > A controlling service worker could intercept a page's request and
  /// > redirect it as desired.
  /// > This will actually lead to a real redirect if a service worker sends it
  /// > upstream.
  external static Response redirect(
    String url, [
    int status,
  ]);

  /// The **`json()`** static method of the [Response] interface returns a
  /// `Response` that contains the provided JSON data as body, and a  header
  /// which is set to `application/json`.
  /// The response status, status message, and additional headers can also be
  /// set.
  ///
  /// The method makes it easy to create `Response` objects for returning JSON
  /// encoded data.
  /// [Service workers](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API),
  /// for example, intercept fetch requests made by a browser, and might use
  /// `json()` to construct a `Response` from cached JSON data to return to the
  /// main thread.
  /// The `json()` method can also be used in server code to return JSON data
  /// for
  /// [single page applications](https://developer.mozilla.org/en-US/docs/Glossary/SPA),
  /// and any other applications where a JSON response is expected.
  @JS('json')
  external static Response json_(
    JSAny? data, [
    ResponseInit init,
  ]);

  /// The **`clone()`** method of the [Response] interface creates a clone of a
  /// response object, identical in every way, but stored in a different
  /// variable.
  ///
  /// Like the underlying [ReadableStream.tee] api,
  /// the [Response.body] of a cloned `Response`
  /// will signal backpressure at the rate of the _faster_ consumer of the two
  /// bodies,
  /// and unread data is enqueued internally on the slower consumed `body`
  /// without any limit or backpressure.
  /// Backpressure refers to the mechanism by which the streaming consumer of
  /// data
  /// (in this case, the code that reads the body)
  /// slows down the producer of data (such as the TCP server)
  /// so as not to load large amounts of data in memory
  /// that is waiting to be used by the application.
  /// If only one cloned branch is consumed, then the entire body will be
  /// buffered in memory.
  /// Therefore, `clone()` is one way to read a response twice in sequence,
  /// but you should not use it to read very large bodies
  /// in parallel at different speeds.
  ///
  /// `clone()` throws a `TypeError` if the response body has already been used.
  /// In fact, the main reason `clone()` exists is to allow multiple uses of
  /// body objects (when they are one-use only.)
  external Response clone();

  /// The **`arrayBuffer()`** method of the [Response] interface
  /// takes a [Response] stream and reads it to completion. It returns a promise
  /// that resolves with an `ArrayBuffer`.
  external JSPromise<JSArrayBuffer> arrayBuffer();

  /// The **`blob()`** method of the [Response] interface takes
  /// a [Response] stream and reads it to completion. It returns a promise that
  /// resolves with a [Blob].
  external JSPromise<Blob> blob();

  /// The **`bytes()`** method of the [Response] interface takes a [Response]
  /// stream and reads it to completion.
  /// It returns a promise that resolves with a `Uint8Array`.
  external JSPromise<JSUint8Array> bytes();

  /// The **`formData()`** method of the [Response] interface
  /// takes a [Response] stream and reads it to completion. It returns a promise
  /// that resolves with a [FormData] object.
  ///
  /// > [!NOTE]
  /// > This is mainly relevant to
  /// > [service workers](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API).
  /// > If a user submits
  /// > a form and a service worker intercepts the request, you could for
  /// > example call
  /// > `formData()` on it to obtain a key-value map, modify some fields, then
  /// > send
  /// > the form onwards to the server (or use it locally).
  external JSPromise<FormData> formData();

  /// The **`json()`** method of the [Response] interface takes
  /// a [Response] stream and reads it to completion. It returns a promise which
  /// resolves with the result of parsing the body text as `JSON`.
  ///
  /// Note that despite the method being named `json()`, the result is not JSON
  /// but is instead the result of taking JSON as input and parsing it to
  /// produce a JavaScript object.
  external JSPromise<JSAny?> json();

  /// The **`text()`** method of the [Response] interface takes a [Response]
  /// stream and reads it to completion.
  /// It returns a promise that resolves with a `String`.
  /// The response is _always_ decoded using UTF-8.
  external JSPromise<JSString> text();

  /// The **`type`** read-only property of the [Response] interface contains the
  /// type of the response.
  /// It can be one of the following:
  ///
  /// - `basic`: Normal, same origin response, with all headers exposed except
  ///   "Set-Cookie".
  /// - `cors`: Response was received from a valid cross-origin request.
  ///   [Certain headers and the body](https://fetch.spec.whatwg.org/#concept-filtered-response-cors)
  ///   may be accessed.
  /// - `error`: Network error.
  /// No useful information describing the error is available.
  /// The Response's status is 0, headers are empty and immutable.
  /// This is the type for a Response obtained from `Response.error()`.
  /// - `opaque`: Response for "no-cors" request to cross-origin resource.
  /// [Severely restricted](https://fetch.spec.whatwg.org/#concept-filtered-response-opaque).
  /// - `opaqueredirect`: The fetch request was made with `redirect: "manual"`.
  /// The Response's status is 0, headers are empty, body is null and trailer is
  /// empty.
  ///
  /// > [!NOTE]
  /// > An "error" Response never really gets exposed to script: such a response
  /// > to a [Window.fetch] would reject the promise.
  external ResponseType get type;

  /// The **`url`** read-only property of the [Response] interface contains the
  /// URL of the response.
  /// The value of the `url` property will be the final URL obtained after any
  /// redirects.
  external String get url;

  /// The **`redirected`** read-only property of the [Response] interface
  /// indicates whether or not the response is the result of a request you made
  /// which was redirected.
  ///
  /// > [!NOTE]
  /// > Relying on redirected to filter out redirects makes it easy for a forged
  /// > redirect to prevent your content from working as expected.
  /// > Instead, you should do the filtering when you call [Window.fetch].
  /// > See the example [Disallowing redirects](#disallowing_redirects), which
  /// > shows this being done.
  external bool get redirected;

  /// The **`status`** read-only property of the [Response] interface contains
  /// the
  /// [HTTP status codes](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status)
  /// of the response.
  ///
  /// For example, `200` for success, `404` if the resource could not be found.
  external int get status;

  /// The **`ok`** read-only property of the [Response] interface contains a
  /// Boolean stating whether the response was successful (status in the range
  /// 200-299) or not.
  external bool get ok;

  /// The **`statusText`** read-only property of the [Response] interface
  /// contains the status message corresponding to the HTTP status code in
  /// [Response.status].
  ///
  /// For example, this would be `OK` for a status code `200`, `Continue` for
  /// `100`, `Not Found` for `404`.
  external String get statusText;

  /// The **`headers`** read-only property of the
  /// [Response] interface contains the [Headers] object associated
  /// with the response.
  external Headers get headers;

  /// The **`body`** read-only property of the [Response] interface is a
  /// [ReadableStream] of the body contents.
  external ReadableStream? get body;

  /// The **`bodyUsed`** read-only property of the [Response] interface is a
  /// boolean value that indicates whether the body has been read yet.
  external bool get bodyUsed;
}
extension type ResponseInit._(JSObject _) implements JSObject {
  external factory ResponseInit({
    int status,
    String statusText,
    HeadersInit headers,
  });

  external int get status;
  external set status(int value);
  external String get statusText;
  external set statusText(String value);
  external HeadersInit get headers;
  external set headers(HeadersInit value);
}