fireDOMChange(el) and waitForIdle(el)

fire-dom-change.js

function fireDOMChange(el, options={attributes: false, childList: true, subtree: true}) {
  const observer = new MutationObserver(list =>  el.dispatchEvent(new CustomEvent('dom-change', {detail: list})));
  observer.observe(el, options);
}

function waitForIdle(el, options) {
  options = Object.assign({
      wait: 100, attributes: false, childList: true, subtree: true 
    }, options);
  return new Promise(resolve => {
    const observer = new MutationObserver(list => {
      el.dispatchEvent(new CustomEvent('dom-changed', {detail: list, bubbles: true}));
    });
    observer.observe(el, options);
    const domChangeListener = debounce(debounceFunc, options.wait)();
    function debounceFunc() {
      resolve(el);
      observer.disconnect(el);
      el.removeEventListener('dom-change', domChangeListener);
    }
    el.addEventListener('dom-change', domChangeListener);
  })
}