The simplest way:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<div id="root"></div>
<script src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
<script src="https://unpkg.com/@babel/standalone/babel.min.js"></script>
<script type="text/babel">
class Hello extends React.Component{
render() {
return <p>Hello {this.props.name}</p>;
};
}
ReactDOM.render(
<Hello name="World"/>,
document.getElementById('root'),
);
</script>
</body>
</html>