JQuery

<script src="https://code.jquery.com/jquery-3.3.1.min.js" integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8=" crossorigin="anonymous"></script>

Showdown

<script src="https://cdnjs.cloudflare.com/ajax/libs/showdown/1.8.6/showdown.min.js"></script>