title: Web Socket: cannot detect client connection on internet disconnect
body: <p>I want to detect the client connection if client turn off the internet using web socket. My code is:</p>
  
  <pre><code> //Include util library
      var util = require('util');
      // Include underscore library
      var _ = require('underscore')._;
      //For websocket
  var webSocketServer = new (require('ws')).Server({port: (process.env.PORT || 5000)}),
  webSockets = {} // userID: webSocket
  
  // CONNECT /:userID
  // wscat -c ws://localhost:5000/1
  webSocketServer.on('connection', function (webSocket) 
  {
    var userID = webSocket.upgradeReq.url.substr(1);
    //console.log('User_id is ',userID);
    webSockets[userID] = webSocket
                     util.log('User_id: [' + userID + '] enter in connected users list of [ ' + Object.getOwnPropertyNames(webSockets)+' ]')
                     // Call function which check id exist in letswalkee DB table
                     check_userid(userID);
  
  
                     // Send msg like: [fromUserID, text]    [1, "Hello, World!"]
  webSocket.on('message', function(message) {
  util.log('Received from [' + userID + ']: ' + message)
  var messageArray = JSON.parse(message)
                                      var toUserWebSocket = webSockets[messageArray[0]]
                                      if (toUserWebSocket) {
                                      util.log('Sent to [' + messageArray[0] + ']: ' + JSON.stringify(messageArray))
                                      messageArray[0] = userID
                                      toUserWebSocket.send(JSON.stringify(messageArray))
                                      }
                                      })
  
                     webSocket.on('close', function () 
                     {
                        delete webSockets[userID]
                        util.log('User_id Deleted from connected users: [ ' + userID+' ]');
  
                      })
  webSocket.on('disconnect',function()
    {
     console.log('hello i am disconnected');  
    });
  })
  </code></pre>
  
  <p>I used that code (webSocket.on('disconnect',function()) but did not worked.</p>