Atomics.wait()

The static Atomics.wait() method verifies that a given position in an Int32Array still contains a given value and if so sleeps, awaiting a wakeup or a timeout. It returns a string which is either "ok", "not-equal", or "timed-out".

Note: This operation only works with a shared Int32Array and may not be allowed on the main thread.

Syntax

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

Parameters

typedArray
A shared Int32Array.
index
The position in the typedArray to wait on.
value
The expected value to test.
timeout Optional
Time to wait in milliseconds. Infinity, if no time is provided.

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

Specification
ECMAScript Language Specification (ECMAScript)
#sec-atomics.wait

Browser compatibility

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See also