SharedArrayBuffer.prototype.growable

Baseline Newly available

This feature works across the latest devices and browser versions. This feature might not work in older devices or browser versions. It's been available across browsers since July 2024.

The growable accessor property of SharedArrayBuffer instances returns whether this SharedArrayBuffer can be grow or not.

Description

The growable 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. If a maxByteLength option was set in the constructor, growable will return true; if not, it will return false.

Examples

Note that these examples cannot be run directly from the console or an arbitrary web page, because SharedArrayBuffer is not defined unless its security requirements are met.

Using growable

In this example, we create a 8-byte buffer that is growable to a max length of 16 bytes, then check its growable property, growing it if growable returns true:

const buffer = new SharedArrayBuffer(8, { maxByteLength: 16 });

if (buffer.growable) {
  console.log("SAB is growable!");
  buffer.grow(12);
}

Specifications

Specification
ECMAScript® 2027 Language Specification # sec-get-sharedarraybuffer.prototype.growable

Browser compatibility