JSFiddle - React, Tailwind, and code Playground

JavaScript

// select the target node
var target = document.body,
    timer;
 
// create an observer instance
var observer = new MutationObserver(function(mutations) {
    
   // fired when a mutation occurs
   timer = setTimeout(function () {

      console.log("executed");
      // my_procedure();

   }, 500);  
    
});
 
// configuration of the observer:
var config = { attributes: true, childList: true, characterData: true };
 
// pass in the target node, as well as the observer options
observer.observe(target, config);

// Testing our observer
setTimeout(function() {
    document.body.innerHTML =  "<div>lol 1</div>";
    document.body.innerHTML += "<div>lol 2</div>";
    document.body.innerHTML += "<div>lol 3</div>";
}, 3000);

/* Comment out if you want to add more divs..
setTimeout(function() {
    document.body.innerHTML += "<div>lol 4</div>";
    document.body.innerHTML += "<div>lol 5</div>";
    document.body.innerHTML += "<div>lol 6</div>";
}, 5000);
*/