Atomics.and()

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.

Syntax

js
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

TypeError

Thrown if typedArray is not one of the allowed integer types.

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:

aba & b
000
010
100
111

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

5  0101
1  0001
   ----
1  0001

Examples

Note that these examples cannot be run directly from the console or an arbitrary web page, because SharedArrayBuffer is not defined unless its security requirements are met.

Using Atomics.and()

js
// Create a SharedArrayBuffer with a size in bytes
const sab = new SharedArrayBuffer(1024);
// Create a view and set the value of the 0 index
const ta = new Uint8Array(sab);
ta[0] = 7;

// 7 (0111) AND 10 (1010) = 2 (0010)
console.log(Atomics.and(ta, 0, 10)); // 7, the old value
console.log(Atomics.load(ta, 0)); // 2, the new/current value

Specifications

See also