add frontend files

app/javascript/packs/application.ts

@@ -13,4 +13,3 @@
 // ActiveStorage.start()
 
 import "stylesheets/application"
-import './src/index'

app/javascript/packs/react.ts

@@ -0,0 +1 @@
+import '../src/index'

app/javascript/packs/src/App.tsx

@@ -1,19 +0,0 @@
-import React from "react"
-import {
-  BrowserRouter as Router,
-  Switch,
-  Route,
-} from "react-router-dom";
-
-export const App = () => (
-  <Router>
-    <Switch>
-      <Route path="/about">
-        <div>About!</div>
-      </Route>
-      <Route path="/">
-        <div className="bg-gray-600">Hello World!</div>
-      </Route>
-    </Switch>
-  </Router>
-)

app/javascript/packs/src/index.tsx

@@ -1,13 +0,0 @@
-import React from 'react'
-import ReactDOM from 'react-dom'
-import { App } from './App'
-
-document.addEventListener('DOMContentLoaded', () => {
-  ReactDOM.render(
-    <React.StrictMode>
-      <App />
-    </React.StrictMode>
-    ,
-    document.getElementById('root'),
-  )
-})