Question

I’m trying to load a Google Maps v3 that shows 5000 markers clickable. My JS contains 10 lines per place:

              var myLatlng_4821 = new google.maps.LatLng(43.0754329,-71.4699752);
              var contentString_4821 =  "<b>Place 1</b>";
              var infowindow_4821 = new google.maps.InfoWindow({content: contentString_4821});
              var marker_4821 = new google.maps.Marker({
                                          position: myLatlng_4821, 
                                          map: map, 
                                          icon: image
                                      });
             google.maps.event.addListener(marker_4821, 'click', function() {
                                        infowindow_4821.open(map,marker_4821);
                                      });

So it gives me a 50 000 lines js (5MB). I would love to cache it but heroku doesn’t allow a page to take more than 30s to load so I can’t even cache it once.

Would you have any tricks to load this page faster? I only managed to do it locally (takes 45s~). I have nothing else to load. I use RoR.

Thanks a lot!

SOLUTION (it’s pretty cool).

 var myLatlng = [];
 var infowindow = [];
 var marker = [];

                  function MakeInfoWindowEvent(map, infowindow, marker) {  
                     return function() {  
                        infowindow.open(map, marker);
                     };  
                  }

                  for (var i=0;i < places.length;i++)
                  {   

                        myLatlng[i] = new google.maps.LatLng(places[i][0],places[i][1]);

                         infowindow[i] = new google.maps.InfoWindow({
                                 content: places[i][2]
                             });

                         marker[i] = new google.maps.Marker({
                              position: myLatlng[i],
                              map: map
                          });

                           google.maps.event.addListener(marker[i], 'click', MakeInfoWindowEvent(map, infowindow[i], marker[i]))

                  }
         }

Answer 1

If I understand you correctly, you have the example code repeated 5000 times, with ‘4821’, the lat&lng and the content string differing for each of the 5000 markers?

If so, then you need to change your approach so that its the data that is ‘repeated’ and not the code…

var markers = [
    [43.0754329,-71.4699752,"Info for first marker"],
    [45.0473490,-56.47688356,"Info for second marker"],
    .
    .
    .
    [20.1234384,12.23462566,"Info for last marker"]
];
for(var i=0; i < markers.length; i++){
    var latLng = new google.maps.LatLng(markers[i][0], markers[i][1]);
    var contentString =  markers[i][2];              
    var infowindow = new google.maps.InfoWindow({content: contentString});
    var marker = new google.maps.Marker({
        position: latlng,
        map: map,
        icon: image
    });
    google.maps.event.addListener(marker, 'click', function()
    {
        infowindow.open(map,marker);
    });
}

This would reduce the size of your page by a significant amount, and will probably solve the caching issue.

A word of warning though – the above code merely illustrates how to remove the repeated code and replace it with data lookup, but there may be issues with creating so many InfoWindow instances at once (You would probably be better off creating the InfoWindow inside the listener.
Also, I’m not completely sure about the visiblity of variables in the closures, so you may end up with 5000 markers having the attributes of the last item in the list (slight changes may be required)