geocode_get_city_name_from_lat_lng.js

  if (navigator.geolocation) {
      navigator.geolocation.getCurrentPosition(function (position) {
          var latitude = position.coords.latitude;
          var longitude = position.coords.longitude;
          var coord = new google.maps.LatLng(latitude,longitude);
          
          geocoder = new google.maps.Geocoder();
          
          geocoder.geocode({'latLng': coord}, function(results, status) {
            for (var i = 0; i < results[4].address_components.length; i++) {
                for (var j = 0; j < results[4].address_components[i].types.length; j++) {
                    if(results[4].address_components[i].types[j] == 'locality') {
                        var city_name = results[4].address_components[i].long_name;
                        alert(city_name);
                    }
                }
            }
          });
      });
  } else {
      alert("Geolocation API is not supported in your browser.");
  }