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.


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



A shared Int32Array.


The position in the typedArray to wait on.


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".



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;, 0, 123);
Atomics.notify(int32, 0, 1);


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

Browser compatibility

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See also