Body.arrayBuffer()

The arrayBuffer() method of the Body mixin takes a Response stream and reads it to completion. It returns a promise that resolves with an ArrayBuffer.

Syntax

response.arrayBuffer().then(function(buffer) {
  // do something with buffer
});

Parameters

None.

Return value

A promise that resolves with an ArrayBuffer.

Examples

Playing music

In our fetch array buffer live, we have a Play button. When pressed, the getData() function is run. Note that before playing full audio file will be downloaded. If you need to play ogg during downloading (stream it) - consider HTMLAudioElement:

new Audio("music.ogg").play();

In getData() we create a new request using the Request() constructor, then use it to fetch an OGG music track. We also use AudioContext.createBufferSource to create an audio buffer source. When the fetch is successful, we read an ArrayBuffer out of the response using arrayBuffer(), decode the audio data using AudioContext.decodeAudioData(), set the decoded data as the audio buffer source's buffer (source.buffer), then connect the source up to the AudioContext.destination.

Once getData() has finished running, we start the audio source playing with start(0), then disable the play button so it can't be clicked again when it is already playing (this would cause an error.)

function getData() {
  source = audioCtx.createBufferSource();

  var myRequest = new Request('viper.ogg');

  fetch(myRequest).then(function(response) {
    return response.arrayBuffer();
  }).then(function(buffer) {
    audioCtx.decodeAudioData(buffer, function(decodedData) {
      source.buffer = decodedData;
      source.connect(audioCtx.destination);
    });
  });
};

// wire up buttons to stop and play audio

play.onclick = function() {
  getData();
  source.start(0);
  play.setAttribute('disabled', 'disabled');
}

Reading files

The Response() constructor accepts Files and Blobs, so it may be used to read a File into other formats.

function readFile(file) {
  return new Response(file).arrayBuffer();
}
<input type="file" onchange="readFile(this.files[0])">

Specifications

Specification
Fetch Standard (Fetch)
# ref-for-dom-body-arraybuffer①

Browser compatibility

BCD tables only load in the browser

See also