Điểm đánh dấu cụm với API Google Maps, vị trí từ cơ sở dữ liệu

Tôi đã tìm thấy nó! Đây là giải pháp. Đây là tệp javascript được cập nhật:

    var customIcons = {
                type1: {
                  icon: 'icon_type1.png'
                },
                type2: {
                  icon: 'icon_type2.png'
                },
                type3: {
                  icon: 'icon_type3.png'
                },
                type4: {
                  icon: 'icon_type4.png'
                }
        };

        function initMap() {
          var cluster = [];
          var map = new google.maps.Map(document.getElementById("map"), {
            center: new google.maps.LatLng(0, 0),
            zoom: 1,
            mapTypeId: 'roadmap'
          });
    var infowindow = new google.maps.InfoWindow();

          // Change this depending on the name of your PHP file
          downloadUrl('https://my-website.com/the-sweet-sweet-xml-info.php', function(data) {
            var xml = data.responseXML;
            var markers = xml.documentElement.getElementsByTagName("marker");
            for (var i = 0; i < markers.length; i++) {
              var name = markers[i].getAttribute("name");
              var address = markers[i].getAttribute("address");
              var type = markers[i].getAttribute("type");
              var point = new google.maps.LatLng(
                  parseFloat(markers[i].getAttribute("lat")),
                  parseFloat(markers[i].getAttribute("lng")));

              var html= "<b>" + 
              markers[i].getAttribute("name") + 
              "</b> <br/>" + 
              markers[i].getAttribute("address");

              var icon = customIcons[type] || {};
              var marker = new google.maps.Marker({
                map: map,
                position: point,
                icon: icon.icon,
              });
              google.maps.event.addListener(marker, 'click', (function(marker, i) {
                            return function() {
                                infowindow.setContent(
                                "<b>" + 
                                markers[i].getAttribute("name") + 
                                "</b> <br/>" + 
                                markers[i].getAttribute("address")
                                );
                                infowindow.open(map, marker);

                                //This sends information from the clicked icon back to the serverside code
                                document.getElementById("setlatlng").innerHTML = markers[i].getAttribute("name");
                            }
                        })(marker, i));
              cluster.push(marker);
            }

            var options = {
                  imagePath: '/location-of-cluster-icons/m'
              };

            var mc = new MarkerClusterer(map,cluster,options);
          });
        }

        function bindInfoWindow(marker, map, infoWindow, html) {
          google.maps.event.addListener(marker, 'click', function() {
            infoWindow.setContent(html);
            infoWindow.open(map, marker);

          });
        }

        function downloadUrl(url, callback) {
          var request = window.ActiveXObject ?
              new ActiveXObject('the-sweet-sweet-xml-info.php') :
              new XMLHttpRequest;

          request.onreadystatechange = function() {
            if (request.readyState == 4) {
              request.onreadystatechange = doNothing;
              callback(request, request.status);
            }
          };

          request.open('GET', url, true);
          request.send(null);
        }

        function doNothing() {}