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


new SharedArrayBuffer()
new SharedArrayBuffer(length)


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.


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);


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

Browser compatibility

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See also