Node.js抛出一个错误，说：发送后无法设置标题

Question

我在学习node.js.下面的代码取自应该工作的一本书。它抛出http.js:704 throw new Error('Can\'t set headers after they are sent.')如果我访问本地主机：8080 /走狗/聊天

var express = require('express'); 
var http = require('http'); 
var app = express(); 
var server = http.createServer(app); 
var io = require('socket.io').listen(server); 
var catchPhrases = ['Why I oughta...', 'Nyuk Nyuk Nyuk!', 'Poifect!', 'Spread out!', 
'Say a few syllables!', 'Soitenly!']; 

app.set('view engine', 'jade'); 
app.set('view options', { layout: true }); 
app.set('views', __dirname + '/views'); 

app.get('/stooges/chat', function(req, res, next) { 
res.render('chat'); 
}); 

io.sockets.on('connection', function(socket) { 
var sendChat = function(title, text) { 
    socket.emit('chat', { 
     title: title, 
     contents: text 
    }); 
}; 

setInterval(function() { 
    var randomIndex = Math.floor(Math.random()*catchPhrases.length) 
    sendChat('Stooge', catchPhrases[randomIndex]); 
}, 5000); 

sendChat('Welcome to Stooge Chat', 'The Stooges are on the line'); 
socket.on('chat', function(data){ 
    sendChat('You', data.text); 
}); 
}); 

app.get('/?', function(req, res){ 
res.render('index'); 
}); 

var port = 8080; 
server.listen(port); 
console.log('Listening on port ' + port); 

哪条线，在上面的代码触发错误？为什么？

UPDATE： 我注释掉线var io = require('socket.io').listen(server);，似乎是已导致错误的一个。

UPDATE： 按照要求通过robertklep，这里的聊天模板：

extends layout 

block scripts 
script(type='text/javascript', src='/socket.io/socket.io.js') 
script(type='text/javascript') 
    var socket = io.connect('http://192.168.1.34:8080'); 
    socket.on('chat', function(data) { 
     document.getElementById('chat').innerHTML = 
     '<p><b>' + data.title + '</b>: ' + data.contents + '</p>'; 
    }); 
    var submitChat = function(form) { 
     socket.emit('chat', {text: form.chat.value}); 
     return false; 
    }; 

block content 
div#chat 

form(onsubmit='return submitChat(this);') 
    input#chat(name='chat', type='text') 
    input(type='submit', value='Send Chat') 

Answer 1

因此，原来我用socket.io的版本错误。我更新了pakcage.json中的依赖从0.9.10到0.9.14，它工作。谢谢您的帮助！