When creating a quick react component in an html page, you will need to use babel to translate the jsx into something readable.
from : https://reactjs.org/docs/cdn-links.html
and babel:
<script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></scri
<!-- Load Babel -->
<script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>