Atomics.store()

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.store() static method stores a given value at the given position in the array and returns that value.

Try it

// Create a SharedArrayBuffer with a size in bytes
const buffer = new SharedArrayBuffer(16);
const uint8 = new Uint8Array(buffer);
uint8[0] = 5;

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

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

Syntax

Atomics.store(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 store a value in.
value: The number to store.

Return value

The value that has been stored.

Exceptions

TypeError: Thrown if typedArray is not one of the allowed integer types.
RangeError: Thrown if index is out of bounds in the typedArray.

Examples

Using store()

const sab = new SharedArrayBuffer(1024);
const ta = new Uint8Array(sab);

Atomics.store(ta, 0, 12); // 12

Specifications

Specification
ECMAScript® 2026 Language Specification # sec-atomics.store

Browser compatibility

	Desktop					Mobile						Server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	WebView Android	Deno	Node.js
`store`	68	79	78	55	15.2	89	79	63	15.2	15.0	89	1.0	8.10.0