JSFiddle - React, Tailwind, and code Playground

HTML

<div id="top">top</div>
<script>
  doesFileExist('https://ajax.googleapis.com/ajax/libs/nonexistingfile.js');

  function doesFileExist(urlToFile) {
    var xhr = new XMLHttpRequest();
    xhr.open('HEAD', urlToFile, false);
    xhr.send();

    if (xhr.status == "404") {
      console.log("File doesn't exist");
      var script = document.createElement('script')
      script.src = 'https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js'
      document.head.append(script)

      return false;
    } else {
      console.log("File exists");
      return true;
    }
  }

</script>



<script>
//this is printed out of a variable as a bunch of inline jquery code
$("#top").fadeOut();
</script>

CSS

#top { background-color: green };