Браузерс глобальные

<script src="https://unpkg.com/react/umd/react.production.min.js" crossorigin></script>

<script
  src="https://unpkg.com/react-dom/umd/react-dom.production.min.js"
  crossorigin></script>

<script
  src="https://unpkg.com/react-bootstrap@next/dist/react-bootstrap.min.js"
  crossorigin></script>

<script>var Alert = ReactBootstrap.Alert;</script>
Successful Swan