This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

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.




The size in byte to check.

Return value

A Boolean indicating whether the operation is lock free.


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


Specification Status Comment
ECMAScript Shared Memory and Atomics
The definition of 'Atomics.isLockFree' in that specification.
Draft Initial definition.

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support No support [2] No support 46 (46) [1] No support No support No support
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support No support 46.0 (46) [1] No support No support No support

[1] This feature is disabled by a preference setting. In about:config, set javascript.options.shared_memory to true

[2] The implementation is under development and needs these runtime flags: --js-flags=--harmony-sharedarraybuffer --enable-blink-feature=SharedArrayBuffer

See also


© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

Atomics Experimental JavaScript Method Shared Memory