server.js:

var express = require('express') , wsio = require('websocket.io') /** * Create express app. */ var app = express.createServer(); /** * Attach websocket server. */ var ws = wsio.attach(app); /** * Serve our code */ app.use(express.static('public')) /** * Listening on connections */ var positions = {} , total = 0 ws.on('connection', function (socket) { // we give the socket an id socket.id = ++total; // we send the positions of everyone else socket.send(JSON.stringify(positions)); socket.on('message', function (msg) { try { var pos = JSON.parse(msg); } catch (e) { return; } positions[socket.id] = pos; broadcast(JSON.stringify({ type: 'position', pos: pos, id: socket.id })); }); socket.on('close', function () { delete positions[socket.id]; broadcast(JSON.stringify({ type: 'disconnect', id: socket.id })); }); function broadcast (msg) { for (var i = 0, l = ws.clients; i < l; i++) { // we avoid sending a message to the same socket that broadcasts if (socket.id != ws.clients[i].id) { // we call `send` on the other clients ws.clients[i].send(msg); } } } }); /** * Listen */ app.listen(3000);

index.html:

     
  
WebSocket cursors
  

运行后却无法看到光标，我用的书上源码也无法解决问题。疑惑好久了，求解答？