showing awit is not synchronous

example.js

class Foo {
  constructor(foo) {
    this.foo = foo
  }

  async execUntilStop(callback) {
    const timeoutLoopCallback = () => {
      if (this.stopExec) return;
      callback({ data: 'data' });
      setTimeout(timeoutLoopCallback, 10);
    };
    setTimeout(timeoutLoopCallback, 10);

    return { data: 'data'};
  }

  stop() {
    this.stopExec = true;
  }
}

const myFunc = async function (num) {
  let callbackCalled = false;
  const callback = () => callbackCalled = true;
  foo = new Foo('foo');
  foo.execUntilStop(callback);
  const hasCallbackCalled = async () => callbackCalled;

  while(!(await hasCallbackCalled())){
    console.log('in loop ', num);
    null;
  }
  foo.stop()
  return 'success!';
};

myFunc(1).then((result) => console.log(result))
myFunc(2).then((result) => console.log(result))

/* console output:
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
in loop  2
in loop  1
*/