code: function connectBrowser (subscriptions, backlog, host, done_cb, secure) {
  
      // Associate the right port
      var websocket_uri;
      if(secure == true) {
          websocket_uri ='wss://' + host + ':1885/mqtt';
      }
      else {
          websocket_uri ='ws://' + host + ':1884/mqtt';
      }
  
      // Create client
      var client = new mqtt_lib.Client(websocket_uri, generateRandomClientId());
      // Register callback for connection lost
      client.onConnectionLost = function() {
          // TODO try to reconnect
      };
      // Register callback for received message
      client.onMessageArrived = function (message) {
          // Execute all the appropriate callbacks:
          // the ones specific to this channel with a single parameter (message)
          // the ones associated to a wildcard channel, with two parameters (message and channel)
          var cbs = findCallbacks(subscriptions, message.destinationName);
          if (cbs!==undefined) {
              cbs.forEach(function(cb) {
                  if (Object.keys(subscriptions).indexOf(message.destinationName)!==-1)
                      cb(message.payloadString);
                  else
                      cb(message.payloadString, message.destinationName);
              });
          }
      };
      // Connect
      client.connect({onSuccess: function() {
          // Execute optional done callback passing true
          if (done_cb!==undefined)
              done_cb(true);
          // Execute the backlog of operations performed while the client wasn't connected
          backlog.forEach(function(e) {
              e.op.apply(this, e.params);
          });
      },
          onFailure: function() {
              // Execute optional done callback passing false
              if (done_cb!==undefined)
                  done_cb(false);
              else
                  console.error('There was a problem initializing nutella.');
          }});
      return client;
  }
docs: Helper function that connects the MQTT client in the browser