The Atomics.wait() static method verifies that a given position in an Int32Array 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 a shared Int32Array or BigInt64Array and may not be allowed on the main thread. For a non-blocking, asynchronous version of this method, see Atomics.waitAsync().


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



A shared Int32Array or BigInt64Array.


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".



Thrown if typedArray is not a shared Int32Array.


Thrown if index is out of bounds in the typedArray.


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
# sec-atomics.wait

Browser compatibility

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See also