客户端代码（client.html）：

var socket = io.connect('localhost:80');

服务端（server.js）：

io = require('socket.io').listen("80",{origins:'*'});

在本地可以正常运行，放到本地服务器，提示

XMLHttpRequest cannot load http://localhost/socket.io/?E... No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://jess.dev' is therefore not allowed access. The response had HTTP status code 404.