如何在React中从express-session获取会话cookie

// 后端代码（使用express框架）
const express = require('express');
const session = require('express-session');
const app = express();

// 使用express-session中间件进行会话管理
app.use(session({
  secret: 'your-secret-key',
  resave: false,
  saveUninitialized: true,
}));

// 路由处理函数
app.get('/getCookie', (req, res) => {
  // 从req.session中获取会话cookie的值
  const sessionCookie = req.session.cookie;

  // 将会话cookie作为响应返回给前端
  res.json({ cookie: sessionCookie });
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

// 前端代码（使用React）
import React, { useEffect, useState } from 'react';
import axios from 'axios';

const App = () => {
  const [cookie, setCookie] = useState('');

  useEffect(() => {
    // 发送HTTP请求到后端获取会话cookie
    axios.get('http://localhost:3000/getCookie', { withCredentials: true })
      .then(response => {
        // 从响应中获取会话cookie的值
        const sessionCookie = response.data.cookie;
        setCookie(sessionCookie);
      })
      .catch(error => {
        console.error(error);
      });
  }, []);

  return (
    <div>
      <p>会话cookie: {cookie}</p>
    </div>
  );
};

export default App;