我怎样才能在从JavaScript的TCP套接字通信吗？

我在想怎么限制它是AJAX应用程序有轮询更新时，这将是理想的是javascript才能够建立一个真正的双向连接到服务器。我不知道是否有一个浏览器插件，可以使一个TCP连接，这样我可以传递数据流入和流出的浏览器插件的整合的JavaScript的一些方法。

I'm thinking about how limiting it is for AJAX apps to have to poll for updates, when what would be ideal is for javascript to be able to set up a real two way connection to the server. I'm wondering if there is some method of integrating javascript with a browser plugin that can make a tcp connection so that I could pass data into and out of the browser plugin.