Watching for changes to a DOM node

watch.js

//See https://www.smashingmagazine.com/2019/04/mutationobserver-api-guide/

var target = document.querySelector('#wrap'); //the parent element you wish to watch
var my_callback_done = false; //flag to avoid running our callback repeatedly

// 1. Create an observer instance
var observer = new MutationObserver(function(mutations) {
    if(my_callback_done) return;

    //Do things here
    console.log('Running callback')
        
    
    my_callback_done = true;
    
});
// 2. Configuration of the observer. In this case, watch for new or removed elements anywhere inside our target
var config = { subtree: true, childList: true };

// 3. Start the observer
observer.observe(target, config);