2 ways to dynamically load scripts in JavaScript

injectScript.js

export default (source) => {
  source || return;
  const newScript = document.createElement("script");
  newScript.async = true;
  newScript.src = source;
  const s0 = document.getElementsByTagName('script')[0];
  s0.parentNode.insertBefore(newScript, s0);
}

loadScript.js

export default ({ id, src, onLoad, d = document, s = 'script' }) => {
  if (d.getElementById(id)) {
    return;
  }
  const js = d.createElement(s);
  js.id = id;
  if (onLoad) {
    js.onload = onLoad;
  }
  js.src = src;
  js.async = true;
  js.defer = true;
  const scripts = d.getElementsByTagName(s)[0];
  if (scripts) {
    scripts.parentNode.insertBefore(js, scripts);
  } else {
    document.body.appendChild(js);
  }
};