dynamicallyLoadJSAndWait.js

// dynamically load a script and wait for load event
async function loadScript(url) {
  return new Promise((resolve, reject) => {
    let ourScript = document.createElement('script');

    ourScript.addEventListener('load', () => {
      console.log('script was loaded');
      resolve('awesome');
    });

    ourScript.addEventListener('error', () => {
      console.log('something went wrong loading ourScript');
      reject('sad');
    });

     // add your script's src here
    ourScript.src = url;
    document.head.appendChild(ourScript);
  });
}

loadScript('https://cdn.jsdelivr.net/npm/...')
  .then((result) => console.log(result))
  .catch((error) => console.error(error));