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.
Atomics.and()
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Syntax
Atomics.and(typedArray, index, value)
Parameters
-
typedArray -
An integer typed array. One of
Int8Array,Uint8Array,Int16Array,Uint16Array,Int32Array,Uint32Array,BigInt64Array, orBigUint64Array. -
index -
The position in the
typedArrayto 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, iftypedArrayis not one of the allowed integer types. - Throws a
RangeError, ifindexis out of bounds in thetypedArray.
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 5, the old value Atomics.load(ta, 0); // 1
Specifications
| Specification |
|---|
| ECMAScript Language Specification # sec-atomics.and |
Browser compatibility
| Desktop | Mobile | Server | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | Deno | Node.js | |
and |
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
16-17
Support was removed to mitigate
speculative execution side-channel attacks (Windows blog).
|
78
57
Support was disabled by default to mitigate
speculative execution side-channel attacks (Mozilla Security Blog).
55-57
46-55
|
No
|
No
|
15.2
Like
SharedArrayBuffer,
Atomics is gated behind COOP/COEP. For more detail, read
Making your website "cross-origin isolated" using COOP and COEP.
10.1-11.1
|
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
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
Support was disabled by default to mitigate
speculative execution side-channel attacks (Mozilla Security Blog).
55-57
46-55
|
No
|
15.2
Like
SharedArrayBuffer,
Atomics is gated behind COOP/COEP. For more detail, read
Making your website "cross-origin isolated" using COOP and COEP.
10.3-11.3
|
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.
|
1.0
|
8.10.0
|
See also
© 2005–2022 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Atomics/and
