class（login.js)
class LoginClass extends React.Component{ render(){ return ( <h2>LoginClass-Class</h2> ) } } ReactDOM.render(<LoginClass />,document.getElementById('root'));
html
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Insert title here</title> <link rel="icon" href="img/favicon.ico" type="image/x-icon" /> <script src="js/react.development.js"></script> <script src="js/react-dom.development.js"></script> <script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script> <script src="/js/login.js" type="text/babel"></script> </head> <body> <div id="root"></div> </body> </html>