Body

The Body mixin of the Fetch API represents the body of the response/request, allowing you to declare what its content type is and how it should be handled.

Body is implemented by both Request and Response. This provides these objects with an associated body (a stream), a used flag (initially unset), and a MIME type (initially the empty byte sequence).

Properties

Body.body Read only

A simple getter used to expose a ReadableStream of the body contents.

Body.bodyUsed Read only

A Boolean that indicates whether the body has been read.

Methods

Body.arrayBuffer()

Takes a Response stream and reads it to completion. It returns a promise that resolves with an ArrayBuffer.

Body.blob()

Takes a Response stream and reads it to completion. It returns a promise that resolves with a Blob.

Body.formData()

Takes a Response stream and reads it to completion. It returns a promise that resolves with a FormData object.

Body.json()

Takes a Response stream and reads it to completion. It returns a promise that resolves with a JSON object.

Body.text()

Takes a Response stream and reads it to completion. It returns a promise that resolves with a USVString (text). The response is always decoded using UTF-8.

Examples

The example below uses a simple fetch call to grab an image and display it in an <img> tag. You'll notice that since we are requesting an image, we need to run Body.blob() (Response implements body) to give the response its correct MIME type.

HTML Content

<img class="my-image" src="https://wikipedia.org/static/images/project-logos/frwiki-1.5x.png">

JS Content

var myImage = document.querySelector('.my-image');
fetch('https://upload.wikimedia.org/wikipedia/commons/7/77/Delete_key1.jpg')
	.then(res => res.blob())
	.then(res => {
		var objectURL = URL.createObjectURL(res);
		myImage.src = objectURL;
});

Specifications

Browser compatibility

[1] Behind a preference starting with version 34.

[2] Readable streams are currently enabled in Firefox, but hidden behind the dom.streams.enabled and javascript.options.streams prefs.

See also

• ServiceWorker API
• HTTP access control (CORS)
• HTTP