SharedArrayBuffer.prototype.byteLength

The byteLength accessor property represents the length of an SharedArrayBuffer in bytes.

Syntax

sab.byteLength

Description

The byteLength property is an accessor property whose set accessor function is undefined, meaning that you can only read this property. The value is established when the shared array is constructed and cannot be changed.

Examples

var sab = new SharedArrayBuffer(1024);
sab.byteLength; // 1024

Specifications

Specification Status Comment
ECMAScript Latest Draft (ECMA-262)
The definition of 'SharedArrayBuffer.prototype.byteLength' in that specification.
Draft Initial definition in ES2017.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support601 No2

573 4

55 — 57

46 — 555

No No10.1 —?
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support601601 ?

573 4

55 — 57

46 — 555

No No ?

1. 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.

2. Support was removed to mitigate speculative execution side-channel attacks (Windows blog).

3. Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog).

4. 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.

5. 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.

See also

Document Tags and Contributors

 Contributors to this page: wbamberg, fscholz, chrisdavidmills
 Last updated by: wbamberg,