wait for element to load javascript

1var checkExist = setInterval(function() {
2   if ($('#the-canvas').length) {
3      console.log("Exists!");
4      clearInterval(checkExist);
5   }
6}, 100); // check every 100ms
7

1document.addEventListener("DOMContentLoaded", function(event) { 
2  //do work
3});

1loading = setInterval(function () {
2    if (document.getElementById("myElement")) {
3        // Element Has Loaded, Put your code here!
4        clearInterval(loading);
5    }
6}, 100); // Checks every 100ms(0.1s)

1document.addEventListener('DOMContentLoaded', (event) => {
2  //the event occurred
3})
4

1var checkExist = setInterval(function() {
2   if ($('#my-element').length) {
3      console.log("Exists!");
4      clearInterval(checkExist);
5   }
6}, 100); // check every 100ms
7