W3cubDocs

Atomics.exchange()

The Atomics.exchange() static method exchanges 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 between the read of the old value and the write of the new value.

Try it

Syntax

Atomics.exchange(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 exchange a value.
value: The number to exchange.

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.

Examples

Using exchange()

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

Atomics.exchange(ta, 0, 12); // returns 0, the old value
Atomics.load(ta, 0); // 12

Specifications

Specification
ECMAScript Language Specification # sec-atomics.exchange

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
`exchange`	68	79	78	55	15.2	89	79	63	15.2	15.0	89	1.0	8.10.0