如何使用Codeigniter Google Maps V3 API库在infowindow中显示选项卡

I am using Codeigniter Google Maps V3 API library to display markers from database on map and so far it works great.

Problem is that I have multiple markers with identical coordinates. So, for example, I have three markers at one location but on map I see only one and get only one infowindow.

I did research and found that It is possible to create infowindow with multiple tabs with infoBubble JS library. Here is a good simple code for adding infoBubble and I wanted to start with just that for beggining.

I created simple contoller that displays map with one marker:

public function index()
        {
                $this->load->library('googlemaps');
                $this->load->helper('url');

                $config['center'] = "37.4419, -122.1419";
                $config['zoom'] = "12";
                $this->googlemaps->initialize($config);

                $marker = array();
                $marker['position'] = '37.429, -122.1419';
                $this->googlemaps->add_marker($marker);
                $data['map'] = $this->googlemaps->create_map();

                $this->load->view('maps_view2', $data);
        }

and it works fine. So now I added

$config['onload'] = 'var  infoBubble = new InfoBubble({
              maxWidth: 300
            });

            var div = document.createElement("DIV");
            div.innerHTML = "Hello";

            infoBubble.addTab("Tab 1", div);
            infoBubble.addTab("Tab 2", "This is tab 2");

            google.maps.event.addListener(marker, "click", function() {
              if (!infoBubble.isOpen()) {
                infoBubble.open(map, marker);
              }
            });';

to my controller. Basically it simply adds JS code snipet to function initialize_map(). I also added <script type="text/javascript" src="<?php echo base_url() ?>src/infobubble.js"></script> to my view.

Comparing example that I used for code snipet with my sites source code I get the same code but there is no infoBubble...

Would appreciate if someone could hepl me understand where is the problem.

this should work

var infowindow = new google.maps.InfoWindow({
                      content:""
                    });
                        marker.setMap(map);
                        marker.addListener('mouseover', function() {
                        infowindow.open(map, marker);
                    });