files/en-us/web/javascript/reference/global_objects/atomics/and/index.md

metadata

title: Atomics.and()
short-title: and()
slug: Web/JavaScript/Reference/Global_Objects/Atomics/and
page-type: javascript-static-method
browser-compat: javascript.builtins.Atomics.and
sidebar: jsref

The Atomics.and() static 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.

{{InteractiveExample("JavaScript Demo: Atomics.and()")}}

// Create a SharedArrayBuffer with a size in bytes
const buffer = new SharedArrayBuffer(16);
const uint8 = new Uint8Array(buffer);
uint8[0] = 7;

// 7 (0111) AND 2 (0010) = 2 (0010)
console.log(Atomics.and(uint8, 0, 2));
// Expected output: 7

console.log(Atomics.load(uint8, 0));
// Expected output: 2

Syntax

Atomics.and(typedArray, index, value)

Parameters

• typedArray
  • : An integer typed array. One of {{jsxref("Int8Array")}}, {{jsxref("Uint8Array")}}, {{jsxref("Int16Array")}}, {{jsxref("Uint16Array")}}, {{jsxref("Int32Array")}}, {{jsxref("Uint32Array")}}, {{jsxref("BigInt64Array")}}, or {{jsxref("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

• {{jsxref("TypeError")}}
  • : Thrown if typedArray is not one of the allowed integer types.
• {{jsxref("RangeError")}}
  • : Thrown 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 5, the old value
Atomics.load(ta, 0); // 1

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{jsxref("Atomics")}}
• {{jsxref("Atomics.or()")}}
• {{jsxref("Atomics.xor()")}}