Node - Push notification when browser closed

I'm new to node and socket.io. I just have done a chrome extension with push notification. In that i'm facing a issue the notification is not sending when chrome browser closed. The server notifies something like below and the notification is not sending.

info  - transport end (socket end)
debug - set close timeout for client kgcuzAOgn5-lrnuQI0Qb
debug - cleared close timeout for client kgcuzAOgn5-lrnuQI0Qb
debug - cleared heartbeat interval for client kgcuzAOgn5-lrnuQI0Qb
debug - discarding transport

here is my code

server

io.sockets.on( 'connection', function ( socket ) {
fs.watch( 'example.xml', function ( curr, prev ) {
  fs.readFile( 'example.xml', function ( err, data ) {
    if ( err ) throw err;    
  parser.parseString( data );
});
 });

  parser.addListener('end', function( result ) {

    // adding the time of the latest update
    //result.time = new Date();
    socket.volatile.emit( 'notification' , result );
  });
});

Client

var socket = new io.connect('http://website:8000');
console.log('client connected');

socket.on('notification', function(data){
console.log("message recieved1 = "+data);

    console.log("message recieved = "+data);
    showNotification(data)
    chrome.browserAction.setBadgeText({ text : "1" });


});

 function showNotification(data){ 
var havePermission = window.webkitNotifications.checkPermission();
  if (havePermission == 0) {
    // 0 is PERMISSION_ALLOWED     

var notification = webkitNotifications.createNotification(
  'http://website.com/favicon.ico',  // icon url - can be relative
  'Hello!',  // notification title
  data  // notification body text
);
// Hide the notification after the configured duration.
    //setTimeout(function(){ notification.cancel(); }, 5000);

    notification.onclick = function () {
      window.open("http://website.com/favicon.gif");
      notification.close();
     resetBadgeText();
    }
   chrome.browserAction.setBadgeText({"text":"1"});
    notification.show();
  } else {
      window.webkitNotifications.requestPermission();
  }
 }

Pls help me to solve this issue.