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SharedArrayBuffer.sharedArrayBuffer

Note that 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([length])

Parameters

length: 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 (ECMA-262) The definition of 'SharedArrayBuffer constructor' in that specification.

Browser compatibilityUpdate compatibility data on GitHub

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
`SharedArrayBuffer()` constructor	68 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 79 16 — 17 Support was removed to mitigate speculative execution side-channel attacks (Windows blog).	79 79 57 Disabled Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog). Disabled From version 57: this feature is behind the `javascript.options.shared_memory` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config. 55 — 57 46 — 55 Disabled Disabled From version 46 until version 55 (exclusive): this feature is behind the `javascript.options.shared_memory` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	No	No	10.1 — 11

	Mobile
	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`SharedArrayBuffer()` constructor	60 — 63 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.	60 — 63 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 79 57 Disabled Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog). Disabled From version 57: this feature is behind the `javascript.options.shared_memory` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config. 55 — 57 46 — 55 Disabled Disabled From version 46 until version 55 (exclusive): this feature is behind the `javascript.options.shared_memory` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	No	10.3 — 11	No No 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.

	Server
	Node.js
`SharedArrayBuffer()` constructor	8.10.0