---
title: AudioBuffer.duration
slug: Web/API/AudioBuffer/duration
tags:
  - API
  - AudioBuffer
  - Property
  - Reference
  - Web Audio API
  - duration
browser-compat: api.AudioBuffer.duration
---
{{ APIRef("Web Audio API") }}

The **`duration`** property of the {{ domxref("AudioBuffer")
    }} interface returns a double representing the duration, in seconds, of the PCM data
stored in the buffer.

## Syntax

```js
var myArrayBuffer = audioCtx.createBuffer(2, frameCount, audioCtx.sampleRate);
myArrayBuffer.duration;
```

### Value

A double.

## Example

```js
// Stereo
var channels = 2;

// Create an empty two second stereo buffer at the
// sample rate of the AudioContext
var frameCount = audioCtx.sampleRate * 2.0;
var myArrayBuffer = audioCtx.createBuffer(2, frameCount, audioCtx.sampleRate);

button.onclick = function() {
  // Fill the buffer with white noise;
  // just random values between -1.0 and 1.0
  for (var channel = 0; channel < channels; channel++) {
    // This gives us the actual ArrayBuffer that contains the data
    var nowBuffering = myArrayBuffer.getChannelData(channel);
    for (var i = 0; i < frameCount; i++) {
      // Math.random() is in [0; 1.0]
      // audio needs to be in [-1.0; 1.0]
      nowBuffering[i] = Math.random() * 2 - 1;
    }
  }

  console.log(myArrayBuffer.duration);
}
```

## Specifications

{{Specifications}}

## Browser compatibility

{{Compat}}

## See also

- [Using the Web Audio
  API](/en-US/docs/Web/API/Web_Audio_API/Using_Web_Audio_API)
