SharedArrayBuffer() constructor

Note: SharedArrayBuffer was disabled by default in all major browsers on 5 January, 2018 in response to Spectre. Chrome re-enabled it in v67 on platforms where its site-isolation feature is enabled to protect against Spectre-style vulnerabilities.

The SharedArrayBuffer() is used to create a SharedArrayBuffer object representing a generic, fixed-length raw binary data buffer, similar to the ArrayBuffer object.

Syntax

new SharedArrayBuffer()
new SharedArrayBuffer(length)

Parameters

length Optional: The size, in bytes, of the array buffer to create.

Return value

A new SharedArrayBuffer object of the specified size. Its contents are initialized to 0.

Examples

Always use the new operator to create a SharedArrayBuffer

SharedArrayBuffer constructors are required to be constructed with a new operator. Calling a SharedArrayBuffer constructor as a function without new will throw a TypeError.

var sab = SharedArrayBuffer(1024);
// TypeError: calling a builtin SharedArrayBuffer constructor
// without new is forbidden

var sab = new SharedArrayBuffer(1024);

Specifications

Specification
ECMAScript Language Specification (ECMAScript) # sec-sharedarraybuffer-constructor

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`SharedArrayBuffer`	68 60-63 Chrome disabled SharedArrayBuffer on January 5, 2018 to help reduce the efficacy of speculative side-channel attacks. This was a temporary removal while mitigations were put in place.	79 16-17 Support was removed to mitigate speculative execution side-channel attacks (Windows blog).	79 57 Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog). 55-57 46-55	No	No	10.1-11	60-63 Chrome disabled SharedArrayBuffer on January 5, 2018 to help reduce the efficacy of speculative side-channel attacks. This is intended as a temporary measure until other mitigations are in place.	89 `SharedArrayBuffer` is gated behind COOP/COEP. For more detail, read Making your website "cross-origin isolated" using COOP and COEP. 60-63 Chrome disabled SharedArrayBuffer on January 5, 2018 to help reduce the efficacy of speculative side-channel attacks. This is intended as a temporary measure until other mitigations are in place.	79 57 Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog). 55-57 46-55	No	10.3-11	15.0 `SharedArrayBuffer` is gated behind COOP/COEP. For more detail, read Making your website "cross-origin isolated" using COOP and COEP.