SharedArrayBuffer object is used to represent a generic, fixed-length raw binary data buffer, similar to the
ArrayBuffer object, but in a way that they can be used to create views on shared memory. Unlike an
SharedArrayBuffer cannot become detached.
SharedArrayBuffer object of the specified size. Its contents are initialized to 0.
To share memory using
SharedArrayBuffer objects from one agent in the cluster to another (an agent is either the web page’s main program or one of its web workers),
postMessage and structured cloning is used.
The structured clone algorithm accepts
TypedArrays mapped onto
SharedArrayBuffers. In both cases, the
SharedArrayBuffer object is transmitted to the receiver resulting in a new, private SharedArrayBuffer object in the receiving agent (just as for
ArrayBuffer). However, the shared data block referenced by the two
SharedArrayBuffer objects is the same data block, and a side effect to the block in one agent will eventually become visible in the other agent.
var sab = new SharedArrayBuffer(1024); worker.postMessage(sab);
Shared memory can be created and updated simultaneously in workers or the main thread. Depending on the system (the CPU, the OS, the Browser) it can take a while until the change is propagated to all contexts. To synchronize, atomic operations are needed.
var sab = SharedArrayBuffer(1024); // TypeError: calling a builtin SharedArrayBuffer constructor // without new is forbidden
var sab = new SharedArrayBuffer(1024);
SharedArrayBufferconstructor's length property whose value is 1.
SharedArrayBuffer instances inherit from
SharedArrayBufferwhose contents are a copy of this
SharedArrayBuffer's bytes from
begin, inclusive, up to
end, exclusive. If either
endis negative, it refers to an index from the end of the array, as opposed to from the beginning.
|ECMAScript Latest Draft (ECMA-262) |
The definition of 'SharedArrayBuffer' in that specification.
|Draft||Initial definition in ES2017.|
|Feature||Chrome||Edge||Firefox (Gecko)||Internet Explorer||Opera||Safari|
|Basic support||No support ||No support||55 (55) ||No support||No support||10.1|
| ||No support||No support||52 (52) ||No support||No support||10.1|
|SAB in DataView||No support||No support||53 (53) ||No support||No support||10.1|
|Feature||Android||Chrome for Android||Firefox Mobile (Gecko)||IE Mobile||Opera Mobile||Safari Mobile|
|Basic support||No support||No support||55.0 (55) ||No support||No support||10.1|
| ||No support||No support||52.0 (52) ||No support||No support||10.1|
|SAB in DataView||No support||No support||53.0 (53) ||No support||No support||10.1|
 Enabled by default in Firefox 55. In Firefox version 46 until version 54, this feature is disabled by a preference setting (in about:config, set
 The implementation is under development and needs these runtime flags:
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