index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>Blog Exercise</title>

    <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"
    ></script>
    <!-- babel -->
    <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/6.26.0/babel.min.js"></script>
  </head>
  <body>
    <div id="blog"></div>
  </body>
  <script type="text/babel" src="blog.js"></script>
</html>