Window: fetch() method

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 fetch() method of the Window interface 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.


         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 (

, 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.

Syntax

fetch(resource)
fetch(resource, options)

Return value

A Promise that resolves to a Response object.

Exceptions

AbortError DOMException
NotAllowedError DOMException
TypeError

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");
window
  .fetch(myRequest)
  .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:
js
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:
js
const req = new Request("flowers.jpg", options);
You can also use an object literal as headers in init:
js
const options = {
  headers: {
    "Cache-Control": "max-age=60480",
const req = new Request("flowers.jpg", options);

`Specifications`

Specification
Fetch Standard # fetch-method

`Browser compatibility`

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