ArrayBuffer.prototype.byteLength
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The byteLength accessor property of ArrayBuffer instances returns the length (in bytes) of this array buffer.
Try it
// 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
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-get-arraybuffer.prototype.bytelength |