React.js：useEffect 与窗口调整大小事件侦听器不起作用

Question

我使用此代码来侦听函数组件中的调整大小事件，并在调整窗口大小时重新渲染该组件。问题是，任何一个事件监听器都没有打印出任何内容，所以我认为我对这里如何使用 useEffect 有误解。

  const [dimensions, setDimensions] = React.useState({
    width: window.innerWidth,
    height: window.innerHeight,
  });

  useEffect(() => {
    const handleResize = () => {
      console.log(dimensions.width);
      setDimensions({
        width: window.innerWidth,
        height: window.innerHeight,
      });
      window.addEventListener("load", handleResize, false);
      window.addEventListener("resize", handleResize, false);
    };
  });

Answer 1

import { useState, useEffect } from "react";
// Usage
function App() {
  const size = useWindowSize();
  return (
    <div>
      {size.width}px / {size.height}px
    </div>
  );
}
// Hook
function useWindowSize() {
  // Initialize state with undefined width/height so server and client renders match
  // Learn more here: https://joshwcomeau.com/react/the-perils-of-rehydration/
  const [windowSize, setWindowSize] = useState({
    width: undefined,
    height: undefined,
  });
  useEffect(() => {
    // Handler to call on window resize
    function handleResize() {
      // Set window width/height to state
      setWindowSize({
        width: window.innerWidth,
        height: window.innerHeight,
      });
    }
    // Add event listener
    window.addEventListener("resize", handleResize);
    // Call handler right away so state gets updated with initial window size
    handleResize();
    // Remove event listener on cleanup
    return () => window.removeEventListener("resize", handleResize);
  }, []); // Empty array ensures that effect is only run on mount
  return windowSize;
}

来源

Answer 2

const [dimensions, setDimensions] = React.useState({
    width: window.innerWidth,
    height: window.innerHeight,
  });
console.log(dimensions);
const handleResize = () => {
    setDimensions({
    width: window.innerWidth,
    height: window.innerHeight,
    });
  }
React.useEffect(() => {
  window.addEventListener("resize", handleResize, false);
}, []);