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                <h2>MutationObserver Example - Moving a Node Tree</h2>

<p>This demo uses a Mutation Observer on a node that's part of a node tree that can be moved from its parent and appended to another parent. Notice that the Mutation Observer is still functional even after the node tree is moved.</p>

<div class="container">
  <ul id="myList" class="list">
      <ul id="nestedList" class="list">
        <li class="child">Nectarine</li>

<p><button class="btnStart">Start Observing for Mutations</button> 
  <button class="btnStop" disabled>Stop Observing for Mutations</button></p>
<p><button class="btnChild">Add/Remove a Child Element</button> <button class="dcList">Move the Target List</button></p>



                body {
  padding: 0 20px;
  font-size: 1.2em;

.container {
  min-height: 200px;

button {
  margin: 3px;


                let container = document.querySelector('.container'),
    mList = document.getElementById('nestedList'),
    li = document.querySelectorAll('#myList li')[3],
    btnChild = document.querySelector('.btnChild'),
    btnStart = document.querySelector('.btnStart'),
    btnStop = document.querySelector('.btnStop'),
    btnDc = document.querySelector('.dcList'),
    options = {
      childList: true
    observer = new MutationObserver(mCallback);

function mCallback(mutations) {
  for (let mutation of mutations) {
    if (mutation.type === 'childList') {
      console.log('Mutation Detected: A child element has been added or removed.');

function doLogAndBtn(msg) {
  btnStart.disabled = !btnStart.disabled;
  btnStop.disabled = !btnStop.disabled;

btnStart.addEventListener('click', function () {
  observer.observe(mList, options);
  doLogAndBtn('Observing for mutations: STARTED');
}, false);

btnStop.addEventListener('click', function () {
  doLogAndBtn('Observing for mutations: STOPPED');
}, false);

btnChild.addEventListener('click', function () {
  if (document.querySelector('.child')) {
  } else {
    mList.insertAdjacentHTML('beforeend', '\n<li class="child">Nectarine</li>');
}, false);

btnDc.addEventListener('click', function () {
  console.log('The node has been disconnected!');
  btnDc.disabled = true;
}, false);