loadScript.js

function loadScript(url) {
  return new Promise(function(resolve, reject) {
    try {
      function callback() {
        resolve();
      }
      var s = document.createElement("script");
      s.src = url;
      if (s.addEventListener) {
        s.addEventListener("load", callback, false)
      } else if (s.readyState) {
        s.onreadystatechange = callback
      }
      document.body.appendChild(s);
    } catch (e) {
      reject(e);
    }
  });
}

// await loadScript("https://cdn.jsdelivr.net/npm/[email protected]/tinycolor.js");