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KML with buffer


This sample demonstrates that the ArcGIS API for JavaScript can not only display KML files, but also gives you full access to the features from a KML file. First, add the KML to the map. Then once theKML layer loads, send the graphics to a geometry service to buffer them. Once the features have been buffered, send them to the PopulationSummary Geoprocessing service.This sample also shows how to rerun the buffer with a larger or smaller distance and rerun the population summary.

Note: The KML layer needs to be publicly accessible.


<!DOCTYPE html>
  <meta charset="utf-8">
  <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
  <title>KML with buffer</title>
  <link rel="stylesheet" href="https://js.arcgis.com/3.20/dijit/themes/tundra/tundra.css">
  <link rel="stylesheet" href="https://js.arcgis.com/3.20/esri/css/esri.css">
    body {
      height: 100%;
      width: 100%;
      margin: 0;
      padding: 0;
    #map {
      height: 100%;
      margin: 0;
      overflow: hidden;
      padding: 0;
      position: relative;
    #description {
      height: 160px;
    #info {
      color: #666;
      padding: 10px;
      font-family: sans-serif;
      width: 90%;
      margin: 0 auto;
    #info h3 {
      color: #E4A54F;
      margin: 0;
      padding: 0 0 5px 0;
    #info hr {
      border: 1px solid #666;
    #popWrapper {
      float: right;
    #totalPop {
      font-weight: bold;
      font-size: x-large;
    .ds {
      background: #000;
      overflow: hidden;
      position: absolute;
      z-index: 2;
      bottom: 0;
    #ds-h div {
      width: 100%;
    #ds .o1 {
      filter: alpha(opacity=10);
      opacity: .1;
    #ds .o2 {
      filter: alpha(opacity=8);
      opacity: .08;
    #ds .o3 {
      filter: alpha(opacity=6);
      opacity: .06;
    #ds .o4 {
      filter: alpha(opacity=4);
      opacity: .04;
    #ds .o5 {
      filter: alpha(opacity=2);
      opacity: .02;
    #ds .h1 {
      height: 1px;
    #ds .h2 {
      height: 2px;
    #ds .h3 {
      height: 3px;
    #ds .h4 {
      height: 4px;
    #ds .h5 {
      height: 5px;

  <script src="https://js.arcgis.com/3.20/"></script>
    var map, kml, kmlGeoms, bufferGraphics, gp;
      "esri/map", "esri/layers/KMLLayer", "esri/layers/GraphicsLayer",
      "esri/SpatialReference", "esri/graphic",
      "esri/tasks/GeometryService", "esri/tasks/Geoprocessor",
      "esri/tasks/BufferParameters", "esri/tasks/FeatureSet",
      "esri/symbols/SimpleFillSymbol", "esri/symbols/SimpleLineSymbol",
      "dojo/parser", "dojo/_base/array", "esri/Color", "dojo/_base/connect",
      "dojo/number", "dojo/dom", "dojo/dom-style", "dojo/dom-attr",

      "dijit/layout/BorderContainer", "dijit/layout/ContentPane",
    ], function(
      Map, KMLLayer, GraphicsLayer,
      SpatialReference, Graphic,
      GeometryService, Geoprocessor,
      BufferParameters, FeatureSet,
      SimpleFillSymbol, SimpleLineSymbol, esriConfig,
      parser, arrayUtils, Color, connect,
      number, dom, domStyle, domAttr
    ) {
      //This sample requires a proxy page to handle communications with the ArcGIS Server services. You will need to replace the url below with the location of a proxy on your machine. See the 'Using the proxy page' help topic for details on setting up a proxy page.
      esriConfig.defaults.io.proxyUrl = "/proxy/";
      esriConfig.defaults.io.alwaysUseProxy = false;

      map = new Map("map", {
        basemap: "topo",
        center: [-77.8, 39.3],
        zoom: 10


      // Graphics layer for the buffer
      bufferGraphics = new GraphicsLayer();

      var kmlUrl =
      kml = new KMLLayer(kmlUrl);

      // The geoprocessor
      var gpUrl =
      gp = new Geoprocessor(gpUrl);
        wkid: 102100

      kml.on("load", function(evt) {
        // Collect the line features from the KML layer
        kmlGeoms = arrayUtils.map(evt.layer.getLayers()[0].graphics,
          function(g) {
            return g.geometry;

        // Send to a function to do the buffer

      // Re-calculate the buffer and population when buffer distance changes
      connect.connect(dom.byId("bufferDistance"), "onchange", bufferKML);

      function bufferKML() {
        dom.byId("totalPop").innerHTML = "";
        domStyle.set("loading", "display", "inline-block");
        domAttr.set("bufferDistance", "disabled", true);

        var bufferDistance = dom.byId("bufferDistance").value;
        var params = new BufferParameters();
        params.geometries = kmlGeoms;
        params.distances = [bufferDistance];
        params.bufferSpatialReference = new SpatialReference({
          "wkid": 102100
        params.outSpatialReference = map.spatialReference;
        params.unit = GeometryService.UNIT_STATUTE_MILE;
        params.unionResults = true;
        //This service is for development and testing purposes only. We recommend that you create your own geometry service for use within your applications. 
        var gsUrl =
        var gs = new GeometryService(gsUrl);
        gs.buffer(params, showBuffer);

      function showBuffer(buffer) {
        // Add the buffer graphic to the map
        var polySym = new SimpleFillSymbol()
          .setColor(new Color([56, 102, 164, 0.4]))
            new SimpleLineSymbol()
            .setColor(new Color([56, 102, 164, 0.8]))
        var bufferGraphic = new Graphic(buffer[0], polySym);

        // Send buffer to runction to calculate population

      function calcPop(aoi) {
        // Create a feature set for the population zonal stats GP service
        var fset = new FeatureSet();
        fset.features = [aoi];

        var params = {
          "inputPoly": fset
        gp.execute(params, handlePop);

      function handlePop(result) {
        if (result[0] && result[0].value.features[0].attributes.hasOwnProperty(
            'SUM')) {
          var pop = number.format((result[0].value.features[0].attributes.SUM)
            .toFixed() + '');
          dom.byId('totalPop').innerHTML = pop;
        } else {
          alert("Unable to get population summary. Please try again.");
        domStyle.set("loading", "display", "none");
        domAttr.set("bufferDistance", "disabled", false);

<body class="tundra">
  <div data-dojo-type="dijit/layout/BorderContainer" data-dojo-props="design:'headline',gutters:false"
    style="width: 100%; height: 100%; margin: 0;">
    <div id="description" data-dojo-type="dijit/layout/ContentPane" data-dojo-props="region:'top'">
      <div id="info">
        <h3>Buffer a KML Layer and the Send Result To a Geoprocessing Service</h3>
        KML layers in the ArcGIS API for JavaScript give you full access to the features
        in a KML file. For this app, a KML file representing most of the Chesapeake and Ohio Canal 
        near Washington, DC is added to the map. The features from the KML layer
        are first buffered using a geometry service and then population within the buffer
        is calculated via a geoprocessing service.
        <hr />
        <div id="feedback">
          Buffer Distance (miles):
          <select id="bufferDistance">
          <option selected>1</option>
          <div id="popWrapper">
            <span id="loading"><img src="images/loading_orange.gif" /> </span>
            <span id="totalPop"></span> people within buffer.
    <div id="map" data-dojo-type="dijit/layout/ContentPane" data-dojo-props="region:'center'">
      <div id="ds">
        <div id="ds-h">
          <div class="ds h1 o1"></div>
          <div class="ds h2 o2"></div>
          <div class="ds h3 o3"></div>
          <div class="ds h4 o4"></div>
          <div class="ds h5 o5"></div>