events2.js

const someReallyAwesomeFunction = () => {
  
  //some process that you want to know when it is finished in an async way.
  
  //After we are finished with the process, then we can push an event
  // with custom events we can attach what ever data we need to pass.
  let myEvent = new CustomEvent('customEventName', { 
    detail: {
      obj: 'that you can pass with the event!',
      pass: 'what ever you want'
    },
    // stick your options here
    bubbles: true,
    cancelable: false
  };

  this.dispatchEvent(myEvent);
};

// Events follow the capture and bubble flow, so you can't know if it isn't attached to something in that flow.
someobj.addEventListener('customeEventName', (e) => console.log(e.detail) );

line:21 custom*e*EventName