JAVASCRIPT

wait for element to load

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

wait for element to load javascript

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

wait for element to be loaded

function waitForElementLoad(selector) {
  return new Promise((resolve, reject) => {
    let el = document.querySelector(selector);
    if (el) {
      resolve(el);
      return;
    }
    new MutationObserver((mutationRecords, observer) => {
      // Query for elements matching the specified selector
      Array.from(document.querySelectorAll(selector)).forEach((element) => {
        resolve(element);
        //Once we have resolved we don't need the observer anymore.
        observer.disconnect();
      });
    }).observe(document.documentElement, {
      childList: true,
      subtree: true,
    });
  });
}