typedArray

An Int32Array or BigInt64Array that views a SharedArrayBuffer.

index

The position in the typedArray to wait on.

value

The expected value to test.

timeout Optional

Time to wait in milliseconds. NaN (and values that get converted to NaN, such as undefined) becomes Infinity. Negative values become 0.

A string which is either "ok", "not-equal", or "timed-out".

TypeError

Thrown in one of the following cases:

• If typedArray is not an Int32Array or BigInt64Array that views a SharedArrayBuffer.
• If the current thread cannot be blocked (for example, because it's the main thread).

RangeError

Thrown if index is out of bounds in the typedArray.

Given a shared Int32Array:

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).

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:

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

• Atomics
• Atomics.waitAsync()
• Atomics.notify()