Atomics.xor()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since December 2021.

The Atomics.xor() static method computes a bitwise XOR 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.

Try it

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

// 7 (0111) XOR 2 (0010) = 5 (0101)
console.log(Atomics.xor(uint8, 0, 2));
// Expected output: 7

console.log(Atomics.load(uint8, 0));
// Expected output: 5

Syntax

js
Atomics.xor(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 XOR.

value

The number to compute the bitwise XOR 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 XOR operation yields 1, if a and b are different. The truth table for the XOR operation is:

a b a ^ b
0 0 0
0 1 1
1 0 1
1 1 0

For example, a bitwise XOR of 5 ^ 1 results in 0100 which is 4 in decimal.

5  0101
1  0001
   ----
4  0100

Examples

Using xor

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

Atomics.xor(ta, 0, 1); // returns 5, the old value
Atomics.load(ta, 0); // 4

Specifications

Specification
ECMAScript® 2025 Language Specification
# sec-atomics.xor

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
xor

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support

See also