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".

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

• Throws a TypeError, if typedArray is not a shared Int32Array.
• Throws a RangeError, if index is out of bounds in the typedArray.

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

• Atomics
• Atomics.notify()