fetch() global function

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.

Note: This feature is available in Web Workers.

The global fetch() method starts the process of fetching a resource from the network, returning a promise that is fulfilled once the response is available.

The promise resolves to the Response object representing the response to your request.

A fetch() promise only rejects when the request fails, for example, because of a badly-formed request URL or a network error. A fetch() promise does not reject if the server responds with HTTP status codes that indicate errors (404, 504, etc.). Instead, a then() handler must check the Response.ok and/or Response.status properties.

The fetch() method is controlled by the connect-src directive of Content Security Policy rather than the directive of the resources it's retrieving.

Note: The fetch() method's parameters are identical to those of the Request() constructor.


fetch(resource, options)



This defines the resource that you wish to fetch. This can either be:

  • A string or any other object with a stringifier — including a URL object — that provides the URL of the resource you want to fetch.
  • A Request object.
options Optional

An object containing any custom settings you want to apply to the request. The possible options are:

attributionReporting Experimental

Indicates that you want the request's response to be able to register a JavaScript-based attribution source or attribution trigger. attributionReporting is an object containing the following properties:


A boolean. If set to true, the request's response is eligible to register an attribution source. If set to false, it isn't.


A boolean. If set to true, the request's response is eligible to register an attribution trigger. If set to false, it isn't.

Note: See the Attribution Reporting API for more details.


Any body that you want to add to your request: this can be a Blob, an ArrayBuffer, a TypedArray, a DataView, a FormData, a URLSearchParams, string object or literal, or a ReadableStream object. This latest possibility is still experimental; check the compatibility information to verify you can use it. Note that a request using the GET or HEAD method cannot have a body.

browsingTopics Experimental

A boolean specifying that the selected topics for the current user should be sent in a Sec-Browsing-Topics header with the associated request. See Using the Topics API for more details.


A string indicating how the request will interact with the browser's HTTP cache. The possible values, default, no-store, reload, no-cache, force-cache, and only-if-cached, are documented in the article for the cache property of the Request object.


Controls what browsers do with credentials (cookies, HTTP authentication entries, and TLS client certificates). Must be one of the following strings:

  • omit: Tells browsers to exclude credentials from the request, and ignore any credentials sent back in the response (e.g., any Set-Cookie header).
  • same-origin: Tells browsers to include credentials with requests to same-origin URLs, and use any credentials sent back in responses from same-origin URLs. This is the default value.
  • include: Tells browsers to include credentials in both same- and cross-origin requests, and always use any credentials sent back in responses.

    Note: Credentials may be included in simple and "final" cross-origin requests, but should not be included in CORS preflight requests.


Any headers you want to add to your request, contained within a Headers object or an object literal with String values. Note that some names are forbidden.

Note: The Authorization HTTP header may be added to a request, but will be removed if the request is redirected cross-origin.


Contains the subresource integrity value of the request (e.g., sha256-BpfBw7ivV8q2jLiT13fxDYAe2tJllusRSZ273h2nFSE=).


The keepalive option can be used to allow the request to outlive the page. Fetch with the keepalive flag is a replacement for the Navigator.sendBeacon() API.


The request method, e.g., "GET", "POST". The default is "GET". Note that the Origin header is not set on Fetch requests with a method of HEAD or GET. Any string which is a case-insensitive match for one of the methods in RFC 9110 will be uppercased automatically. If you want to use a custom method (like PATCH), you should uppercase it yourself.


The mode you want to use for the request, e.g., cors, no-cors, or same-origin.


Specifies the priority of the fetch request relative to other requests of the same type. Must be one of the following strings:


A high priority fetch request relative to other requests of the same type.


A low priority fetch request relative to other requests of the same type.


Automatically determine the priority of the fetch request relative to other requests of the same type (default).


How to handle a redirect response:


Automatically follow redirects. Unless otherwise stated the redirect mode is set to follow.


Abort with an error if a redirect occurs.


Caller intends to process the response in another context. See WHATWG fetch standard for more information.


A string specifying the referrer of the request. This can be a same-origin URL, about:client, or an empty string.


Specifies the referrer policy to use for the request. May be one of no-referrer, no-referrer-when-downgrade, same-origin, origin, strict-origin, origin-when-cross-origin, strict-origin-when-cross-origin, or unsafe-url.


An AbortSignal object instance; allows you to communicate with a fetch request and abort it if desired via an AbortController.

Return value

A Promise that resolves to a Response object.


AbortError DOMException

The request was aborted due to a call to the AbortController abort() method.

NotAllowedError DOMException

Thrown if use of the Topics API is specifically disallowed by a browsing-topics Permissions Policy, and a fetch() request was made with browsingTopics: true.


Can occur for the following reasons:

Reason Failing examples
Blocked by a permissions policy Use of the Attribution Reporting API is blocked by a attribution-reporting Permissions-Policy, and a fetch() request was made with attributionReporting specified.
Invalid header name.
// space in "C ontent-Type"
const headers = {
  'C ontent-Type': 'text/xml',
  'Breaking-Bad': '<3',
fetch('https://example.com/', { headers });
Invalid header value. The header object must contain exactly two elements.
const headers = [
  ['Content-Type', 'text/html', 'extra'],
fetch('https://example.com/', { headers });
Invalid URL or scheme, or using a scheme that fetch does not support, or using a scheme that is not supported for a particular request mode.
fetch('blob://example.com/', { mode: 'cors' });
URL includes credentials.
Invalid referrer URL.
fetch('https://example.com/', { referrer: './abc\u0000df' });
Invalid modes (navigate and websocket).
fetch('https://example.com/', { mode: 'navigate' });
If the request cache mode is "only-if-cached" and the request mode is other than "same-origin".
fetch('https://example.com/', {
  cache: 'only-if-cached',
  mode: 'no-cors',
If the request method is an invalid name token or one of the forbidden headers ('CONNECT', 'TRACE' or 'TRACK').
fetch('https://example.com/', { method: 'CONNECT' });
If the request mode is "no-cors" and the request method is not a CORS-safe-listed method ('GET', 'HEAD', or 'POST').
fetch('https://example.com/', {
  method: 'CONNECT',
  mode: 'no-cors',
If the request method is 'GET' or 'HEAD' and the body is non-null or not undefined.
fetch('https://example.com/', {
  method: 'GET',
  body: new FormData(),
If fetch throws a network error.


In our Fetch Request example (see Fetch Request live) we create a new Request object using the relevant 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.

const myImage = document.querySelector("img");

const myRequest = new Request("flowers.jpg");

  .then((response) => {
    if (!response.ok) {
      throw new Error(`HTTP error! Status: ${response.status}`);

    return response.blob();
  .then((response) => {
    myImage.src = URL.createObjectURL(response);

In our Fetch Request with init example (see Fetch Request init live) we do the same thing except that we pass in an options object when we invoke fetch(). In this case, we can set a Cache-Control value to indicate what kind of cached responses we're okay with:

const myImage = document.querySelector("img");
const reqHeaders = new Headers();

// A cached response is okay unless it's more than a week old
reqHeaders.set("Cache-Control", "max-age=604800");

const options = {
  headers: reqHeaders,

// Pass init as an "options" object with our headers.
const req = new Request("flowers.jpg", options);

fetch(req).then((response) => {
  // ...

You could also pass the init object in with the Request constructor to get the same effect:

const req = new Request("flowers.jpg", options);

You can also use an object literal as headers in init:

const options = {
  headers: {
    "Cache-Control": "max-age=60480",

const req = new Request("flowers.jpg", options);


Fetch Standard
# fetch-method

Browser compatibility

BCD tables only load in the browser

See also