在div中显示内容更改的日期和时间(vanilla js)

// The item we want to watch
var watch = document.querySelector('.active')

// The new observer with a callback to execute upon change
var observer = new MutationObserver((mutationsList) => {
  console.log(new Date().toUTCString())
});

// Start observing the element using these settings
observer.observe(watch, { childList: true, subtree: true });

// Some random test function to modify the element
// This will make sure the callback is running correctly
setInterval(() => {
  watch.innerHTML = Math.random() * 1000
}, 1000)

<ul>
  <li class="active"></li>
</ul>