provides a WebSocket-like object in browser

 SockJS-client is a browser JavaScript library that provides a WebSocket-like
 object. SockJS gives you a coherent, cross-browser, Javascript API which
 creates a low latency, full duplex, cross-domain communication channel between
 the browser and the web server.
 .
 Under the hood SockJS tries to use native WebSockets first. If that fails it
 can use a variety of browser-specific transport protocols and presents them
 through WebSocket-like abstractions.
 .
 SockJS is intended to work for all modern browsers and in environments which
 don't support the WebSocket protocol -- for example, behind restrictive
 corporate proxies.
 .
 Node.js is an event-based server-side JavaScript engine.