gistfile1.js

// In controller
@map_markers = []
  @estates.each do |key,value|
    marker = {location: key.location, estates: value.collect(&:id),property: key.name}
    @map_markers << marker
end

// In the view
<%= hidden_field_tag :coordiates,"",id: "coordinates", data: { markers: @map_markers, boundaries: @location } %>


// Javascript file (map initializer)

// getting markers coordinates from the hidden field
   var markers = $("#coordinates").data('markers');

for (i = 0; i < markers.length; i++) {
   marker = new google.maps.Marker({
      position: new google.maps.LatLng(markers[i]['location']['lat'], markers[i]['location']['lng']),
      map: map,
      icon: 'http://maps.google.com/mapfiles/kml/pal3/icon56.png',//'http://chart.apis.google.com/chart?chst=d_map_pin_icon&chld=home|FF0000',
      label: '<i class="map-icon-real-estate-agency"></i>',
      animation: google.maps.Animation.DROP,
      title: markers[i]['property']+" ("+markers[i]['estates'].length+") Estates"
      });