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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

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet Deno Node.js
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
79
57
Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog).
55-57
46-55
No
No
preview
SharedArrayBuffer is gated behind COOP/COEP. For more detail, read Making your website "cross-origin isolated" using COOP and COEP.
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.
1.0
8.10.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer/SharedArrayBuffer