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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

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); // false

Specifications

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

Browser compatibilityUpdate compatibility data on GitHub

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	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.	16 16 Support was removed to mitigate speculative execution side-channel attacks (Windows blog).	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	No	10.1 — ?

	Mobile
	Android webview	Chrome for Android	Edge Mobile	Firefox for Android	Opera for Android	iOS Safari	Samsung Internet
Basic support	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	No	No

	Server
	Node.js
Basic support	8.10.0