Response

The Response interface of the Fetch API represents the response to a request.

You can create a new Response object using the 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 fetch().

Constructor

Response(): Creates a new Response object.

Properties

Response.body Read only: A ReadableStream of the body contents.
Response.bodyUsed Read only: Stores a boolean value that declares whether the body has been used in a response yet.
Response.headers Read only: The Headers object associated with the response.
Response.ok Read only: A boolean indicating whether the response was successful (status in the range 200–299) or not.
Response.redirected Read only: Indicates whether or not the response is the result of a redirect (that is, its URL list has more than one entry).
Response.status Read only: The status code of the response. (This will be 200 for a success).
Response.statusText Read only: The status message corresponding to the status code. (e.g., OK for 200).
Response.trailers: A Promise resolving to a Headers object, associated with the response with Response.headers for values of the HTTP Trailer header.
Response.type Read only: The type of the response (e.g., basic, cors).
Response.url Read only: The URL of the response.

Methods

Response.arrayBuffer(): Returns a promise that resolves with an ArrayBuffer representation of the response body.
Response.blob(): Returns a promise that resolves with a Blob representation of the response body.
Response.clone(): Creates a clone of a Response object.
Response.error(): Returns a new Response object associated with a network error.
Response.formData(): Returns a promise that resolves with a FormData representation of the response body.
Response.json(): Returns a promise that resolves with the result of parsing the response body text as JSON.
Response.redirect(): Creates a new response with a different URL.
Response.text(): Returns a promise that resolves with a text representation of the response body.

Examples

Fetching an image

In our basic fetch example (run example live) we use a simple fetch() call to grab an image and display it in an <img> element. The fetch() call returns a promise, which resolves to the Response object associated with the resource fetch operation.

You'll notice that since we are requesting an image, we need to run Response.blob to give the response its correct MIME type.

const image = document.querySelector('.my-image');
fetch('flowers.jpg')
.then(response => response.blob())
.then(blob => {
  const objectURL = URL.createObjectURL(blob);
  image.src = objectURL;
});

You can also use the Response() constructor to create your own custom Response object:

const response = new Response();

An Ajax Call

Here we call a PHP program file that generates a JSON string, displaying the result as a JSON value, including simple error handling.

// Function to do an Ajax call
const doAjax = async () => {
  const response = await fetch('Ajax.php'); // Generate the Response object
  if (response.ok) {
    const jsonValue = await response.json(); // Get JSON value from the response body
    return Promise.resolve(jsonValue);
  } else {
    return Promise.reject('*** PHP file not found');
  }
}

// Call the function and output value or error message to console
doAjax().then(console.log).catch(console.log);

Specifications

Specification
Fetch Standard # response-class

Browser compatibility

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