_geocoder.js.erb

var geocoder = new google.maps.Geocoder();

jQuery(document).ready(function($) {

  $('#map_location').submit(function(e) {
    e.preventDefault();
  })

  window.mapKnitter.getMap().on('drag',function(e) {
    $("#map_lat").val(window.mapKnitter.getMap().getCenter().lat);
    $("#map_lon").val(window.mapKnitter.getMap().getCenter().lng);
    $("#map_zoom").val(window.mapKnitter.getMap().getZoom());
  })

  $("#map_location").autocomplete({
    autoFocus: true,
    //This bit uses the geocoder to fetch address values
    source: function(request, response) {
      geocoder.geocode( {'address': request.term }, function(results, status) {
        response($.map(results, function(item) {
          return {
            label:  item.formatted_address,
            value: item.formatted_address,
            latitude: item.geometry.location.lat(),
            longitude: item.geometry.location.lng(),
            bounds: item.geometry.bounds
          }
        }));
      })
    },
    //This bit is executed upon selection of an address
    select: function(event, ui) {
      var b = ui.item.bounds
      $("#map_lat").val(ui.item.latitude);
      $("#map_lon").val(ui.item.longitude);
      if (b) {
        window.mapKnitter.getMap().fitBounds([
          [b.getNorthEast().lat(), b.getNorthEast().lng()],
          [b.getSouthWest().lat(), b.getSouthWest().lng()]
          ]);
      } else {
        window.mapKnitter.getMap().panTo([ui.item.latitude,
                                      ui.item.longitude])
        window.mapKnitter.getMap().setZoom(14)
      }
      $("#map_zoom").val(window.mapKnitter.getMap().getZoom());
    }
  });

})