useOnClickOutside

這個 hook 可以檢測指定元素之外的點擊，適用於 Modal 或 Dropdown menus 的元件在點擊元件以外的元素時自動關閉。

JSX
import { useEffect } from 'react';

export default function useOnClickOutside(ref, handler) {
  useEffect(() => {
    const listener = (event) => {
      if (!ref.current || ref.current.contains(event.target)) {
        return;
      }
      handler(event);
    };
    document.addEventListener('mousedown', listener);
    document.addEventListener('touchstart', listener);
    return () => {
      document.removeEventListener('mousedown', listener);
      document.removeEventListener('touchstart', listener);
    };
  }, [ref, handler]);
}

JSX
import { useState, useRef } from 'react';

const App = () => {
  const [isModalOpen, setModalOpen] = useState(false);
  const ref = useRef();

  useOnClickOutside(ref, () => setModalOpen(false));

  return (
    <div ref={ref}>
      {isModalOpen ? (
        <div ref={ref}>👋 Hey, I'm a modal. Click anywhere outside of me to close.</div>
      ) : (
        <button onClick={() => setModalOpen(true)}>Open Modal</button>
      )}
    </div>
  );
};