WebSocket emulation - Javascript client

 SockJS 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.
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 SockJS is intended to work for all modern browsers and in environments which
 don't support WebSocket protocol, for example behind restrictive corporate
 proxies.