Atomics.notify()

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.notify() static method notifies up some agents that are sleeping in the wait queue.

Note: This operation only works with an Int32Array or BigInt64Array that views a SharedArrayBuffer. It will return 0 on non-shared ArrayBuffer objects.

Syntax

js
Atomics.notify(typedArray, index, count)

Parameters

typedArray

An Int32Array or BigInt64Array that views a SharedArrayBuffer.

index

The position in the typedArray to wake up on.

count Optional

The number of sleeping agents to notify. Defaults to Infinity.

Return value

  • Returns the number of woken up agents.
  • Returns 0, if a non-shared ArrayBuffer object is used.

Exceptions

TypeError

Thrown if typedArray is not an Int32Array or BigInt64Array that views a SharedArrayBuffer.

RangeError

Thrown if index is out of bounds in the typedArray.

Examples

Using notify

Given a shared Int32Array:

js
const sab = new SharedArrayBuffer(1024);
const int32 = new Int32Array(sab);

A reading thread is sleeping and waiting on location 0 which is expected to be 0. As long as that is true, it will not go on. However, once the writing thread has stored a new value, it will be notified by the writing thread and return the new value (123).

js
Atomics.wait(int32, 0, 0);
console.log(int32[0]); // 123

A writing thread stores a new value and notifies the waiting thread once it has written:

js
console.log(int32[0]); // 0;
Atomics.store(int32, 0, 123);
Atomics.notify(int32, 0, 1);

Specifications

Specification
ECMAScript Language Specification
# sec-atomics.notify

Browser compatibility

BCD tables only load in the browser

See also