React 19.2

// Before
{isVisible && <Page />}

// After
<Activity mode={isVisible ? 'visible' : 'hidden'}>
  <Page />
</Activity>

function ChatRoom({ roomId, theme }) {
  useEffect(() => {
    const connection = createConnection(serverUrl, roomId);
    connection.on('connected', () => {
      showNotification('Connected!', theme);
    });
    connection.connect();
    return () => {
      connection.disconnect()
    };
  }, [roomId, theme]);
  // ...
}

function ChatRoom({ roomId, theme }) {
  const onConnected = useEffectEvent(() => {
    showNotification('Connected!', theme);
  });
  useEffect(() => {
    const connection = createConnection(serverUrl, roomId);
    connection.on('connected', () => {
      onConnected();
    });
    connection.connect();
    return () => connection.disconnect();
  }, [roomId]); // ✅ 모든 의존성이 선언됨 (Effect Events는 의존성이 아님)
  // ...
}

import { cache, cacheSignal } from 'react';

const dedupedFetch = cache(fetch);

async function Component() {
  await dedupedFetch(url, { signal: cacheSignal() });
}

const { prelude, postponed } = await prerender(<App />, {
  signal: controller.signal,
});
// 나중을 위해 postponed 상태 저장
await savePostponedState(postponed);
// prelude를 클라이언트 또는 CDN으로 전송합니다.

const postponed = await getPostponedState(request);
const resumeStream = await resume(<App />, postponed);
// 스트림을 클라이언트로 전송합니다.

const postponedState = await getPostponedState(request);
const { prelude } = await resumeAndPrerender(<App />, postponedState);
// 완전한 HTML prelude를 CDN으로 전송합니다.

- extends: ['plugin:react-hooks/recommended']
+ extends: ['plugin:react-hooks/recommended-legacy']