Summary
In the first code snippet on this page, useState is called but is not imported in the snippet.
Suggest to improve as:
import { useEffect, useState } from 'react';
import { createConnection } from './chat.js';
function ChatRoom({ roomId }) {
  const [serverUrl, setServerUrl] = useState('https://localhost:1234');
  useEffect(() => {
    const connection = createConnection(serverUrl, roomId);
    connection.connect();
    return () => {
      connection.disconnect();
    };
  }, [serverUrl, roomId]);
  // ...
}Page
https://react.dev/reference/react/useEffect#useeffect
Details
No response