• Create a new wiki page and add this in its content (see also https://reactjs.org/docs/add-react-to-a-website.html):

  {{html}}
  <div id="like_button_container"></div>
  {{/html}}

• Edit the page with the object editor and add a JavaScriptExtension object with this content:

  require.config({
    paths: {
      'react': 'https://unpkg.com/react@16/umd/react.production.min',
      'react-dom': 'https://unpkg.com/react-dom@16/umd/react-dom.production.min'
    }
  })
  
  define('likeButton', ['react'], function(React) {
    'use strict';
  
    class LikeButton extends React.Component {
      constructor(props) {
        super(props);
        this.state = { liked: false };
      }
  
      render() {
        if (this.state.liked) {
          return 'You liked this.';
        }
  
        return React.createElement(
          'button',
          { onClick: () => this.setState({ liked: true }) },
          'Like'
        );
      }
    }
  
    return LikeButton;
  });
  
  require(['react', 'react-dom', 'likeButton'], function(React, ReactDOM, LikeButton) {
    const domContainer = document.querySelector('#like_button_container');
    ReactDOM.render(React.createElement(LikeButton), domContainer);
  });

• Set the JSX object to be loaded "On this page or on demand". That's it!

Result