What's the actual use of the Atomics object in ECMAScript?

Question

The ECMAScript specification defines the Atomics object in the section 24.4.

Among all the global objects this is the more obscure for

Answer 1

I have coded a script using Web Worker and SharedArrayBuffer to demonstrate the use of Atomics:

Then with a separate file worker.js:

// worker.js
onmessage = function(e) {
    e.data[0]++;                 // last line is 981 only? wth?!
    //Atomics.add(e.data,0,1);   // last line is exactly 1000. right...
    console.log(e.data[0]);
}

As you can see, without the mutex guaranteed by Atomics, the addition would not be correctly carried out sometimes.