在使用fetch api时使用socket.io广播消息

fetch('/api/resource', {
  method: 'GET',
  headers: {
    'Content-Type': 'application/json',
  },
})
.then(response => response.json())
.then(data => {
  // 处理返回的数据
})
.catch(error => {
  // 处理请求错误
});

const app = require('express')();
const http = require('http').createServer(app);
const io = require('socket.io')(http);

io.on('connection', socket => {
  console.log('a user connected');

  // 监听前端发送的fetch API请求
  socket.on('fetchRequest', requestData => {
    // 处理请求数据
    const responseData = {
      // 构造返回数据
    };

    // 广播消息给所有连接的客户端
    io.emit('fetchResponse', responseData);
  });

  socket.on('disconnect', () => {
    console.log('user disconnected');
  });
});

http.listen(3000, () => {
  console.log('listening on *:3000');
});

const socket = io();

// 监听后端广播的消息
socket.on('fetchResponse', responseData => {
  // 处理后端广播的数据
});

// 发送fetch API请求给后端
fetch('/api/resource', {
  method: 'GET',
  headers: {
    'Content-Type': 'application/json',
  },
})
.then(response => response.json())
.then(data => {
  // 处理返回的数据
})
.catch(error => {
  // 处理请求错误
});