separate App

src/App.tsx

@@ -0,0 +1,8 @@
+import React from 'react'
+
+export default function App() {
+  const [count, setCount] = React.useState(0)
+  return <button onClick={() => setCount((count) => count + 1)}>
+    count is {count}
+  </button>;
+}

src/main.tsx

@@ -1,12 +1,6 @@
 import React from 'react'
 import ReactDOM from 'react-dom/client'
-
-function App() {
-  const [count, setCount] = React.useState(0)
-  return <button onClick={() => setCount((count) => count + 1)}>
-    count is {count}
-  </button>;
-}
+import App from './App';
 
 const root = document.getElementById('root');
 root && ReactDOM.createRoot(root).render(<React.StrictMode><App /></React.StrictMode>);