docs: 添加了几个图

frontend/Web/index.js

@@ -0,0 +1,28 @@
+const express = require('express');
+const { createServer } = require('node:http');
+const { join } = require('node:path');
+const { Server } = require('socket.io');
+
+const app = express();
+const server = createServer(app);
+const io = new Server(server);
+
+app.get('/', (req, res) => {
+  res.sendFile(join(__dirname, 'index.html'));
+});
+
+io.on('connection', (socket) => {
+  console.log('a user connected');
+  socket.on('disconnect', () => {
+    console.log('user disconnected');
+  });
+  socket.on('chat message', (msg) => {
+    console.log('message: ' + msg);
+    socket.emit('chat message', '[self]'+msg);
+    socket.broadcast.emit('chat message', '[other]'+msg);
+  });
+});
+
+server.listen(3000, () => {
+  console.log('server running at http://localhost:3000');
+});