UNB/ CS/ David Bremner/ teaching/ cs2613/ books/ mdn/ Reference/ Global Objects/ Atomics/ Atomics.wait()

The Atomics.wait() static method verifies that a shared memory location still contains a given value and if so sleeps, awaiting a wake-up notification or times out. It returns a string which is either "ok", "not-equal", or "timed-out".

Note: This operation only works with an Int32Array or BigInt64Array that views a SharedArrayBuffer, and may not be allowed on the main thread. For a non-blocking, asynchronous version of this method, see Atomics.waitAsync.

Syntax

Atomics.wait(typedArray, index, value)
Atomics.wait(typedArray, index, value, timeout)

Parameters

Return value

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

Exceptions

Examples

Using wait()

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);

Specifications

Browser compatibility

See also