Socket.io supports a lot of different transports(also websockets) and it should because websockets are not supported by the most browsers. But for example Google Chrome does already support websockets. I believe that websockets are the transport of the future(but not yet!). When you look at Socket.io 的浏览器支持页面 you will notice that Socket.io does support all the major browsers(some even ancient). The nice thing is that it wraps this around a nice API.