scinote-web/app/javascript/packs/settings/app.jsx

// Run this example by adding <%= javascript_pack_tag 'hello_react' %> to the head of your layout file,
// like app/views/layouts/application.html.erb. All it does is render <div>Hello React</div> at the bottom
// of the page.

import React from 'react';
import ReactDOM from 'react-dom';
import Navigation from '../shared/navigation';
import messages from '../locales/messages';

const App = () => (
  <div>
    <Navigation page='Settings'/>
    ....
  </div>
)

document.addEventListener('DOMContentLoaded', () => {
  ReactDOM.render(
    <App />,
    document.getElementById('root')
  )
})