Querying building information

Obtain information about a building at a location and place a marker above its centroid.
<!DOCTYPE HTML>
<html>
  <head>
    <script src="https://unpkg.com/wrld.js@1.x.x"></script>
    <link href="https://cdnjs.cloudflare.com/ajax/libs/leaflet/1.0.1/leaflet.css" rel="stylesheet" />
  </head>
  
  <body>
  <div style="position: relative">
    <div id="map" style="height: 400px"></div>
    <script>
        var map = Wrld.map("map", "your_api_key_here", {
            center: [37.784079, -122.396762],
            zoom: 18
        });

        function onInitialStreamingComplete() {
            var buildingHighlight = Wrld.buildings.buildingHighlight(
                Wrld.buildings.buildingHighlightOptions()
                    .highlightBuildingAtLocation([37.784079, -122.396762])
                    .informationOnly()
                )
                .addTo(map);
        }

        function onBuildingInformationReceived(event) {
            var buildingInformation = event.buildingHighlight.getBuildingInformation();
            if (buildingInformation !== null) {
                console.log(JSON.stringify(buildingInformation.toJson()));

                var buildingDimensions = buildingInformation.getBuildingDimensions();
                var groundAltitude = buildingDimensions.getBaseAltitude();
                var buildingHeight = (buildingDimensions.getTopAltitude() - groundAltitude);
                var title = "Height: " + buildingHeight.toFixed(2) + " m";
                Wrld.marker(buildingDimensions.getCentroid(), {
                        elevation: buildingHeight,
                        title: title
                   }).addTo(map);

                var contours = buildingInformation.getBuildingContours();
                contours.forEach(function(contour) {
                    var points = contour.getPoints();
                    points.push(points[0]);
                    var polyline = Wrld.polyline(points, {
                        elevation: (contour.getTopAltitude() - groundAltitude),
                        elevationMode: "heightAboveGround",
                        color: "blue"
                        })
                        .addTo(map);
                });
            }
            else {
                console.log("No building information was received for building highlight id: " + event.buildingHighlight.getId());
            }
        }

        map.on("initialstreamingcomplete", onInitialStreamingComplete);
        map.buildings.on("buildinginformationreceived", onBuildingInformationReceived);
    </script>
  </div>
  </body>
</html>