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View Toggle point clustering sample in sandbox
Toggle point clustering


This sample highlights the separation between featureReduction (e.g. clustering) and the renderer of a FeatureLayer. While clustering is used for visualization purposes, it is not a property of the renderer; it is a property of the layer. Therefore, when featureReduction is enabled, the renderer is still applied to the layer. If a renderer is driven by a numeric attribute, then each aggregate graphic is visualized using the average value of the features comprising that cluster. If a UniqueValueRenderer is applied to the layer, then each cluster's color represents the predominant value represented by features comprising the cluster.

Support for feature reduction is limited to the following scenarios:

  • The map must have a spatial reference of Web Mercator or WGS84.
  • FeatureLayer or CSVLayer with point geometries fewer than 50,000 features.
  • FeatureLayer created from a service URL must point to a service that supports pagination.
  • When editing is initiated with the Editor widget, then feature reduction is disabled until the Editor widget is destroyed.


<!DOCTYPE html>


<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no"/>
<title>Toggle FeatureLayer clustering</title>

<link rel="stylesheet" href="https://js.arcgis.com/3.46/esri/css/esri.css">
<script src="https://js.arcgis.com/3.46/"></script>

  html, body, #viewDiv {
    height: 100%;
    width: 100%;
    margin: 0;
    padding: 0;

    top: 0px;
    right: 0px;
    position: absolute;
    z-index: 2;
    opacity: 0.9;
    background-color: whitesmoke;
    padding: 8px;
    font-family: Verdana, Geneva, Arial, Helvetica, sans-serif;
    font-size: 12px;

  ], function(Map, FeatureLayer, PopupTemplate, Legend
  ) {

    var map = new Map("viewDiv", {
      basemap: "gray-vector",
      center: [ -117.9145, 33.9773 ],
      zoom: 9

    // Enable clustering on the layer and add it to the map

    var serviceUrl = "https://services.arcgis.com/V6ZHFr6zdgNZuVG0/arcgis/rest/services/socal_precincts_points_2008/FeatureServer/0";
    var layer = new FeatureLayer(serviceUrl, {
      outFields: [ "P2008_D", "P2008_R", "D_Percent", "R_Percent", "Majority" ],
      infoTemplate: new PopupTemplate({
        title: "Winner: {Majority}",
        description: "{P2008_D} votes for Obama ({D_Percent}%)"
          + "<br>{P2008_R} votes for McCain ({R_Percent}%)"

    map.on("load", function(evt){

      var legend = new Legend({
        map: map,
        layerInfos: [{
          layer: layer,
          title: "Voting precincts (2008)"
      }, "legendDiv");

      var clusteringCheckbox = document.getElementById("use-clustering");
      // toggles clustering on and off in sync with the checkbox
      clusteringCheckbox.addEventListener("click", function(event){
        var checked = event.target.checked;

    // Sets feature reduction on the layer if not previously done so.
    // If indicated, then feature reduction is disabled. The initial
    // feature reduction settings are enabled if indicated.
    function toggleFeatureReduction(yes){
            type: "cluster"
        } else {
      } else {




  <div id="viewDiv"></div>
  <div id="infoDiv">
    <input type="checkbox" id="use-clustering" checked> Use clustering?<br><br>
    <div id="legendDiv"></div>

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