Response: blob() 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.

Note: This feature is available in Web Workers.

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.

Note: If the Response has a Response.type of "opaque", the resulting Blob will have a Blob.size of 0 and a Blob.type of empty string "", which renders it useless for methods like URL.createObjectURL().

Return value

A promise that resolves with a Blob whose data is the body's bytes and the media type is the response's Content-Type header's value.

Exceptions

AbortError DOMException

The request was aborted.

TypeError

Thrown for one of the following reasons:

The response body is disturbed or locked.
There was an error decoding the body content (for example, because the Content-Encoding header is incorrect).

Examples

In our fetch request example (run fetch request live), we create a new request using the Request() constructor, then use it to fetch a JPG. When the fetch is successful, we read a Blob out of the response using blob(), put it into an object URL using URL.createObjectURL(), and then set that URL as the source of an <img> element to display the image.

const myImage = document.querySelector("img");
const myRequest = new Request("flowers.jpg");
fetch(myRequest)
 .then((response) => response.blob())
 .then((myBlob) => {
 const objectURL = URL.createObjectURL(myBlob);
 myImage.src = objectURL;
 });