ArrayBuffer.prototype.byteLength

The byteLength accessor property of {{jsxref("ArrayBuffer")}} instances returns the length (in bytes) of this array buffer.

{{InteractiveExample("JavaScript Demo: ArrayBuffer.prototype.byteLength")}}

```js interactive-example // Create an ArrayBuffer with a size in bytes const buffer = new ArrayBuffer(8);

// Use byteLength to check the size const bytes = buffer.byteLength;

console.log(bytes); // Expected output: 8

## Description

The `byteLength` property is an accessor property whose set accessor function is `undefined`, meaning that you can only read this property. The value is established when the array is constructed and cannot be changed. This property returns 0 if this `ArrayBuffer` has been detached.

## Examples

### Using byteLength

```js
const buffer = new ArrayBuffer(8);
buffer.byteLength; // 8

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• {{jsxref("ArrayBuffer")}}