SharedArrayBuffer.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 December 2021.

The byteLength accessor property of SharedArrayBuffer instances returns the length (in bytes) of this SharedArrayBuffer.

Try it

// Create a SharedArrayBuffer with a size in bytes
const buffer = new SharedArrayBuffer(8);

console.log(buffer.byteLength);
// 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 shared array is constructed and cannot be changed.

Examples

Using byteLength

js
const sab = new SharedArrayBuffer(1024);
sab.byteLength; // 1024

Specifications

Specification
ECMAScript® 2025 Language Specification
# sec-get-sharedarraybuffer.prototype.bytelength

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
byteLength

Legend

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Full support
Full support
No support
No support

See also