Playing with Google Maps

I had to use Google Maps for my current project. Three things that I needed to do:

• show longitude and latitude
• draw a circle (e.g. in radius of 100m)
• move it around that circle.

Geocoding part is just an extra.

    $(function() {
      var map, geocoder, circle, marker;

      function updateLatLng(latlng) {
        document.getElementById("lat").innerHTML = latlng.lat().toFixed(5);
        document.getElementById("lng").innerHTML = latlng.lng().toFixed(5);
      }

      function showAddress() {
        var address = document.getElementById("address").value;
        if (geocoder) {
          geocoder.geocode( {'address': address}, function(results, status) {
            if (status == google.maps.GeocoderStatus.OK) {
              var latlng = results[0].geometry.location;
              map.setCenter(latlng);
              marker.setPosition(latlng);
              updateLatLng(latlng);
              circle.setOptions({center: latlng}); 
            }
            else {
              alert("Geocode not successful: " + status);
            }
          }
          );
        }
        return false;
      }

      function load() {
        var latlng = new google.maps.LatLng(35.68949,  139.69171), 
            myOptions = {
              zoom: 15,
              center: latlng,
              streetViewControl: false,
              mapTypeId: google.maps.MapTypeId.ROADMAP };

        updateLatLng(latlng);

        map = new google.maps.Map(document.getElementById("map"), myOptions);

        /* 
          Create a circle with 100m radius.
          Set it to where the marker is located.
        */
        circle = new google.maps.Circle({
          strokeColor: "#FF0000",
               strokeOpacity: 0.8,
               strokeWidth: 1.5,
               fillColor: "#ff0000",
               fillOpacity: 0.35,
               map: map,
               center: latlng,
               radius: 100
        });

        /* create a new marker and make it draggable  */
        marker = new google.maps.Marker(
            {position:latlng, map:map, draggable:true});

        /* when dragging stars, make the circle disappear */
        google.maps.event.addListener(marker, "dragstart", function() {
          circle.setOptions({fillOpacity:0, strokeOpacity: 0});
        });

        /* when dragging ends, make the circle appear and udpate latlng */
        google.maps.event.addListener(marker, "dragend", function() {
          var latlng = marker.getPosition();
          updateLatLng(latlng);
          circle.setOptions({
            center: latlng, 
            fillOpacity:0.35, 
            strokeOpacity: 0.8});
        });

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

      load();

      window.showAddress = showAddress;
    });