在useEffect中只调用两个函数一次

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

const MyComponent = () => {
  const [data, setData] = useState(null);

  const fetchData = async () => {
    const response = await fetch('https://api.example.com/data');
    const result = await response.json();
    setData(result);
  };

  const subscribeToUpdates = () => {
    // 订阅逻辑
    console.log('Subscribed to updates');
  };

  useEffect(() => {
    fetchData();
    subscribeToUpdates();

    // 清理函数，组件卸载时执行
    return () => {
      // 取消订阅逻辑
      console.log('Unsubscribed from updates');
    };
  }, []); // 空数组表示只在挂载和卸载时执行

  return (
    <div>
      {data ? <div>{JSON.stringify(data)}</div> : <div>Loading...</div>}
    </div>
  );
};

export default MyComponent;