check if browser is WebSocket compatible

anotherVersion.js

$(document).ready(function() {
  if( typeof(WebSocket) != "function" ) {
    // Display error message here !
  }
});

cleanerVersionOfAbove.js

// Check if the user's browser is WebSocket(WS) compatible
// http://bit.ly/SiWEDV for more info
function isBrowserWSCompatible () {
    var isCompatible = false;
    if ("WebSocket" in window) {
      isCompatible = true;
    };
    return isCompatible;
  };

websocket.js

if ("WebSocket" in window) {
  // different ways to create WebSocket using Faye though
  var ws = new WebSocket("ws://example.com/service");
  ws.onopen = function() {
    // Web Socket is connected. You can send data by send() method.
    ws.send("message to send"); ....
  };
  ws.onmessage = function (evt) { var received_msg = evt.data; ... };
  ws.onclose = function() { // websocket is closed. };
} else {
  // the browser doesn't support WebSocket.
}