Observer Element Addition Check

https://usefulangle.com/post/356/javascript-detect-element-added-to-dom

by MegaScience

HTML

<div id="parent"></div>

JavaScript

const observer = new MutationObserver(mutations_list => {
  //console.log(mutations_list, mutation, added_node)
  const test = Array.from(mutations_list).some(mutation => Array.from(mutation.addedNodes).some(added_node => added_node.dataset.addStuff === 'yes'))
  if (test) {
    console.log('success', mutations_list)
    observer.disconnect()
  } else console.log('failure', mutations_list)
})
observer.observe(document.getElementById('parent'), {
  subtree: false,
  childList: true
})
document.querySelector("#parent").innerHTML = '<div id="child" data-add-Stuff="yes">Child</div>';