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Atomics.isLockFree

The static Atomics.isLockFree() method is used to determine whether to use locks or atomic operations. It returns true, if the given size is one of the BYTES_PER_ELEMENT property of integer TypedArray types.

Syntax

Atomics.isLockFree(size)

Parameters

size
The size in bytes to check.

Return value

A Boolean indicating whether the operation is lock free.

Examples

Using isLockFree

Atomics.isLockFree(1); // true
Atomics.isLockFree(2); // true
Atomics.isLockFree(3); // false
Atomics.isLockFree(4); // true
Atomics.isLockFree(5); // false
Atomics.isLockFree(6); // false
Atomics.isLockFree(7); // false
Atomics.isLockFree(8); // true

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
isLockFree 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).
78
78
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 — 11.1
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
isLockFree 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.
57
Disabled
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 — 11.3 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
isLockFree 8.10.0

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Atomics/isLockFree