// Create a cluster layer for a point feature service

clusterLayer = new ClusterFeatureLayer({
    "url": "http://services.arcgis.com/oKgs2tbjK6zwTdvi/arcgis/rest/services/Major_World_Cities/FeatureServer/0",
    "distance": 75,
    "id": "clusters",
    "labelColor": "#fff",
    "resolution": map.extent.getWidth() / map.width,
    "singleTemplate": infoTemplate,
    "useDefaultSymbol": false,
    "zoomOnClick": true,
    "showSingles": true,
    "objectIdField": "FID",
    outFields: ["NAME", "COUNTRY", "POPULATION", "CAPITAL"]
});

map.addLayer(clusterLayer);

	// options:
    //     url:    string
    //        URL string. Required. Will generate clusters based on Features returned from map service.
    //     outFields:    Array?
    //        Optional. Defines what fields are returned with Features.
    //     objectIdField:    String?
    //        Optional. Defines the OBJECTID field of service. Default is 'OBJECTID'.
    //     where:    String?
    //        Optional. Where clause for query.
    //     useDefaultSymbol:    Boolean?
    //        Optional. Use the services default symbology for single features.
    //     returnLimit:    Number?
    //        Optional. Return limit of features returned from query. Default is 1000.
    //     distance:    Number?
    //         Optional. The max number of pixels between points to group points in the same cluster. Default value is 50.
    //     labelColor:    String?
    //         Optional. Hex string or array of rgba values used as the color for cluster labels. Default value is #fff (white).
    //     labelOffset:    String?
    //         Optional. Number of pixels to shift a cluster label vertically. Defaults to -5 to align labels with circle symbols. Does not work in IE.
    //     resolution:    Number
    //         Required. Width of a pixel in map coordinates. Example of how to calculate:
    //         map.extent.getWidth() / map.width
    //     showSingles:    Boolean?
    //         Optional. Whether or graphics should be displayed when a cluster graphic is clicked. Default is true.
    //     zoomOnClick:    Boolean?
    //         Optional. Will zoom the map when a cluster graphic is clicked. Default is true.
    //     singleSymbol:    MarkerSymbol?
    //         Marker Symbol (picture or simple). Optional. Symbol to use for graphics that represent single points. Default is a small gray SimpleMarkerSymbol.
    //     singleRenderer:    Renderer?
    //         Optional. Can provide a renderer for single features to override the default renderer.
    //     singleTemplate:    PopupTemplate?
    //         PopupTemplate. Optional. Popup template used to format attributes for graphics that represent single points. Default shows all attributes as 'attribute = value' (not recommended).
    //     disablePopup:    Boolean?
    //         Optional. Disable infoWindow for cluster layer. Default is false.
    //     maxSingles:    Number?
    //         Optional. Threshold for whether or not to show graphics for points in a cluster. Default is 1000.
    //     font:    TextSymbol?
    //         Optional. Font to use for TextSymbol. Default is 10pt, Arial.
    //     spatialReference:    SpatialReference?
    //         Optional. Spatial reference for all graphics in the layer. This has to match the spatial reference of the map. Default is 102100. Omit this if the map uses basemaps in web mercator.