React中使用ResizeObserver来观察元素size变化的方法

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

const useResizeObserver = () => {
  const [size, setSize] = useState({ width: 0, height: 0 });
  const elementRef = useRef(null);

  useEffect(() => {
    const resizeObserver = new ResizeObserver(entries => {
      for (let entry of entries) {
        setSize({
          width: entry.contentRect.width,
          height: entry.contentRect.height
        });
      }
    });

    if (elementRef.current) {
      resizeObserver.observe(elementRef.current);
    }

    return () => {
      if (elementRef.current) {
        resizeObserver.unobserve(elementRef.current);
      }
      resizeObserver.disconnect();
    };
  }, []);

  return [elementRef, size];
};

export default useResizeObserver;

import React from 'react';
import useResizeObserver from './useResizeObserver';

const MyComponent = () => {
  const [elementRef, size] = useResizeObserver();

  return (
    <div>
      <div ref={elementRef} style={{ width: '50%', height: '200px', backgroundColor: 'lightblue' }}>
        Resize me!
      </div>
      <p>Width: {size.width}px</p>
      <p>Height: {size.height}px</p>
    </div>
  );
};

export default MyComponent;