SharedArrayBuffer.prototype.maxByteLength

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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 maxByteLength accessor property of SharedArrayBuffer instances returns the maximum length (in bytes) that this SharedArrayBuffer can be grown to.

Description

The maxByteLength 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, set via the maxByteLength option of the SharedArrayBuffer() constructor, and cannot be changed.

If this SharedArrayBuffer was constructed without specifying a maxByteLength value, this property returns a value equal to the value of the SharedArrayBuffer's byteLength.

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 maxByteLength

In this example, we create a 8-byte buffer that is resizable to a max length of 16 bytes, then return its maxByteLength:

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

buffer.maxByteLength; // 16

Specifications

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

Browser compatibility