自定义Hooks复用逻辑

1. useFetch

function useFetch<T>(url: string, options?: RequestInit) {
  const [data, setData] = useState<T | null>(null);
  const [error, setError] = useState<Error | null>(null);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    const controller = new AbortController();
    setLoading(true);

    fetch(url, { ...options, signal: controller.signal })
      .then((res) => {
        if (!res.ok) throw new Error(res.statusText);
        return res.json();
      })
      .then(setData)
      .catch((err) => {
        if (err.name !== 'AbortError') setError(err);
      })
      .finally(() => setLoading(false));

    return () => controller.abort();
  }, [url]);

  return { data, error, loading };
}

2. useLocalStorage

function useLocalStorage<T>(key: string, initialValue: T) {
  const [storedValue, setStoredValue] = useState<T>(() => {
    try {
      const item = window.localStorage.getItem(key);
      return item ? JSON.parse(item) : initialValue;
    } catch {
      return initialValue;
    }
  });

  const setValue = (value: T | ((val: T) => T)) => {
    const valueToStore = value instanceof Function ? value(storedValue) : value;
    setStoredValue(valueToStore);
    window.localStorage.setItem(key, JSON.stringify(valueToStore));
  };

  return [storedValue, setValue] as const;
}

3. useDebounce

function useDebounce<T>(value: T, delay: number): T {
  const [debouncedValue, setDebouncedValue] = useState(value);

  useEffect(() => {
    const timer = setTimeout(() => setDebouncedValue(value), delay);
    return () => clearTimeout(timer);
  }, [value, delay]);

  return debouncedValue;
}

4. useToggle

function useToggle(initial = false) {
  const [value, setValue] = useState(initial);
  const toggle = useCallback(() => setValue((v) => !v), []);
  const setTrue = useCallback(() => setValue(true), []);
  const setFalse = useCallback(() => setValue(false), []);
  return { value, toggle, setTrue, setFalse };
}

5. 设计原则

• 以 use 开头
• 返回值使用数组或对象
• 清理副作用（定时器、事件监听、AbortController）
• 接受 ref 或回调作为参数以避免闭包陷阱