ขอคำแนะนำเกี่ยวกับการทำ google map หน่อยค่ะ อยากให้ช่วยไกด์ในการเขียนโค้ด

<script>
function initialize() {
var mapOptions = {
center: new google.maps.LatLng(13.754059,100.493317),
zoom: 12,
mapTypeId: google.maps.MapTypeId.ROADMAP
};

var map = new google.maps.Map(document.getElementById("map_canvas"),
mapOptions);
}

downloadUrl("dbxml.php", function(data) {
      var markers = data.documentElement.getElementsByTagName("marker");
	  
      for (var i = 0; i < markers.length; i++) {
        var lat = new google.maps.LatLng(parseFloat(markers[i].getAttribute("latitude"));
        var lng = new google.maps.LatLng(parseFloat(markers[i].getAttribute("longitude")));
        var marker = createMarker(markers[i].getAttribute("place_name"), latlng);
		var id_place = markers[i].getAttribute("id_place");
      
       }
	   
     });
  }
  function createMarker(place_name, latitudelongitude,id_place) {
    var marker = new google.maps.Marker(
	{position: latlng,
	map: map,
	icon: "https://dekdee.buu.ac.th/~s52530315/work/1165165831.gif"
	
	});
    google.maps.event.addListener(marker, "click", function() {
      if (infowindow) infowindow.close();
      infowindow = new google.maps.InfoWindow({สถานที่: "+ name_place+ "


      });
       
      infowindow.open(map, marker);
    });
    return marker;
  }

</script>