js 后端调用前端

const WebSocket = require('ws');
const wss = new WebSocket.Server({ port: 8080 });

wss.on('connection', function connection(ws) {
  ws.on('message', function incoming(message) {
    console.log('received: %s', message);
  });

  // 后端主动向前端发送消息
  ws.send('Hello from server!');
});

const socket = new WebSocket('ws://localhost:8080');

socket.addEventListener('open', function (event) {
  socket.send('Hello from client!');
});

socket.addEventListener('message', function (event) {
  console.log('Message from server ', event.data);
});

const express = require('express');
const app = express();

app.get('/events', function (req, res) {
  res.setHeader('Content-Type', 'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Connection', 'keep-alive');

  // 后端主动向前端发送消息
  setInterval(() => {
    res.write(`data: ${new Date().toISOString()}

`);
  }, 1000);
});

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

const eventSource = new EventSource('/events');

eventSource.addEventListener('message', function (event) {
  console.log('Message from server ', event.data);
});