Atomics.and()

The static Atomics.and() method computes a bitwise AND with a given value at a given position in the array, and returns the old value at that position. This atomic operation guarantees that no other write happens until the modified value is written back.

Syntax

Atomics.and(typedArray, index, value)

Parameters

typedArray
An integer typed array. One of Int8Array, Uint8Array, Int16Array, Uint16Array, Int32Array, Uint32Array, BigInt64Array, or BigUint64Array.
index
The position in the typedArray to compute the bitwise AND.
value
The number to compute the bitwise AND with.

Return value

The old value at the given position (typedArray[index]).

Exceptions

  • Throws a TypeError, if typedArray is not one of the allowed integer types.
  • Throws a RangeError, if index is out of bounds in the typedArray.

Description

The bitwise AND operation only yields 1, if both a and b are 1. The truth table for the AND operation is:

a b a & b
0 0 0
0 1 0
1 0 0
1 1 1

For example, a bitwise AND of 5 & 1 results in 0001 which is 1 in decimal.

5  0101
1  0001
   ----
1  0001

Examples

Using and()

const sab = new SharedArrayBuffer(1024);
const ta = new Uint8Array(sab);
ta[0] = 5;

Atomics.and(ta, 0, 1); // returns 0, the old value
Atomics.load(ta, 0);  // 1

Specifications

Specification
ECMAScript (ECMA-262)
The definition of 'Atomics.and' in that specification.

Browser compatibility

DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
andChrome Full support 68
Full support 68
No support 60 — 63
Notes
Notes 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.
Edge Full support 79
Full support 79
No support 16 — 17
Notes
Notes Support was removed to mitigate speculative execution side-channel attacks (Windows blog).
Firefox Full support 78
Full support 78
Full support 57
Notes Disabled
Notes 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.
No support 55 — 57
No support 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.
IE No support NoOpera No support NoSafari No support 10.1 — 11.1WebView Android No support 60 — 63
Notes
No support 60 — 63
Notes
Notes 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.
Chrome Android No support 60 — 63
Notes
No support 60 — 63
Notes
Notes 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.
Firefox Android Full support 57
Notes Disabled
Full support 57
Notes Disabled
Notes 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.
No support 55 — 57
No support 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.
Opera Android No support NoSafari iOS No support 10.3 — 11.3Samsung Internet Android No support No
Notes
No support No
Notes
Notes 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.
nodejs Full support 8.10.0

Legend

Full support
Full support
No support
No support
See implementation notes.
See implementation notes.
User must explicitly enable this feature.
User must explicitly enable this feature.

See also