solution

src/App.tsx

@@ -1,7 +1,62 @@
 import React from 'react';
+//import { useEffect, useState } from 'react';
 
-export const App: React.FC = () => (
-  <div className="App">
-    <p className="App__message">The last pressed key is [Enter]</p>
-  </div>
-);
+// export const App: React.FC = () => {
+//   const [pressedKey, setPressedKey] = useState<string | null>(null);
+
+//   useEffect(() => {
+//     const handleClick = (event: KeyboardEvent) => {
+//       setPressedKey(event.key);
+//     };
+
+//     document.addEventListener('keyup', handleClick);
+
+//     return () => document.removeEventListener('keyup', handleClick);
+//   }, []);
+
+//   return (
+//     <div className="App">
+//       {pressedKey === null ? (
+//         <p className="App__message">Nothing was pressed yet</p>
+//       ) : (
+//         <p className="App__message">The last pressed key is [{pressedKey}]</p>
+//       )}
+//     </div>
+//   );
+// };
+
+type State = {
+  pressedKey: string | null;
+};
+
+export class App extends React.Component<{}, State> {
+  state: State = {
+    pressedKey: null,
+  };
+
+  componentDidMount() {
+    document.addEventListener('keyup', this.handleClick);
+  }
+
+  componentWillUnmount() {
+    document.removeEventListener('keyup', this.handleClick);
+  }
+
+  render() {
+    const { pressedKey } = this.state;
+
+    return (
+      <div className="App">
+        {pressedKey === null ? (
+          <p className="App__message">Nothing was pressed yet</p>
+        ) : (
+          <p className="App__message">The last pressed key is [{pressedKey}]</p>
+        )}
+      </div>
+    );
+  }
+
+  private handleClick = (event: KeyboardEvent) => {
+    this.setState({ pressedKey: event.key });
+  };
+}

src/index.tsx

@@ -2,5 +2,6 @@ import { createRoot } from 'react-dom/client';
 import { App } from './App';
 
 import './index.scss';
+import React from 'react';
 
 createRoot(document.getElementById('root') as HTMLElement).render(<App />);