Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The growable accessor property of SharedArrayBuffer instances represents whether the SharedArrayBuffer can be grow or not.


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.


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!");


Resizable ArrayBuffer and growable SharedArrayBuffer
# sec-get-sharedarraybuffer.prototype.growable

Browser compatibility

BCD tables only load in the browser

See also