Atomics.and() - JavaScript 编辑

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.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

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

BCD tables only load in the browser

See also

• Atomics
• Atomics.or()
• Atomics.xor()