Observe DOM Mutatinos in the document

Observe_DOM_Mutatinos.js

var say = (msg)=>{
  console.log(msg);
}

const observer = new MutationObserver( (mutationList)=>{
  say(mutationList);
});

var targetNode = document.querySelector(nodeSelector);

observer.observe(targetNode, {subtree: true, attributes: true} );