无法更新与socket.io断开连接的用户

Question

用户断开连接时无法更新用户列表，仅在用户连接时更新，我的代码有什么问题？ 如果我有用户A，B，C和C离开房间，那么列表仍然是用户A，B，C，并且必须只是A和B.

SERVER

var app = require('express')();
var express = require('express');
var http = require('http').Server(app);
var io = require('socket.io')(http);
app.use(express.static('./public'));
var users = [];
var nicks = new Array();

    app.get('/', function(req, res){
      res.sendFile(__dirname + '/index.html');
    });


    io.sockets.on('connection', function (socket) {

    socket.on('adduser', function (user) {
        socket.user = user;
        users.push(user);
        updateClients();
    });

    socket.on('disconnect', function () {
        for(var i=0; i<users.length; i++) {
            if(users[i] == socket.user) {
                   delete users[users[i]];
            }
        }
        updateClients(); 
    });

    function updateClients() {
        io.sockets.emit('update', users);
    }

});










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

客户端

   $(document).ready(function() {

     var socket = io();



     socket.on('connect', function (){
            socket.emit('adduser', prompt("What's your name?"));
        });

        var userList = [];

        socket.on('update', function (users){
            userList = users;

                $( "h1" ).remove();
            for(var i=0; i<userList.length; i++) {

             $('#wrap').append("<h1>" + userList[i] + "</h1>"); 
            }
        });

        });