MutationObserver quick test

createObserver.js

function observeElement(element) {
  const config = { attributes: true, childList: true, subtree: true };
  const callback = function(mutationsList, observer) {
    for(let mutation of mutationsList) {
        if (mutation.type === 'childList') {
          const additions = mutation.addedNodes;
          const removals = mutation.removedNodes;
          if (removals.length) {
            console.log('Child nodes were removed:', ...removals);
          }
          if (additions.length) {
            console.log('Child nodes were added:', ...additions);
          }
        }
        else if (mutation.type === 'attributes') {
            console.log('The ' + mutation.attributeName + ' attribute was modified.');
        }
    }
  };

  const observer = new MutationObserver(callback);
  observer.observe(element, config);
}