ArcGIS API for JavaScript ^3.26

require([
  "esri/geometry/Polyline", "esri/SpatialReference", ... 
], function(Polyline, SpatialReference, ... ) {
  new Polyline(new SpatialReference({wkid:4326}));
  ...
});

require([
  "esri/geometry/Polyline", ... 
], function(Polyline, ... ) {
  var polylineJson = {
    "paths":[[[-122.68,45.53], [-122.58,45.55],
    [-122.57,45.58],[-122.53,45.6]]],
    "spatialReference":{"wkid":4326}
  };

  var polyline = new Polyline(polylineJson);
  ...
});

var singlePathPolyline = new Polyline([[-50, 0], [-120, -20], [-130, 0]]);

var map;

require([
  "esri/InfoTemplate",
  "esri/layers/FeatureLayer",
  "esri/map",
  "esri/tasks/query", "dojo/domReady!"
], function (InfoTemplate, FeatureLayer, Map, Query){

  map = new Map("map", {
    basemap: "topo",
    center: [-122.45, 37.75], // longitude, latitude
    zoom: 10
  });

  var infoTemplate = new InfoTemplate("Attributes", "${*}");

  var countiesFeatureLayer = new FeatureLayer("http://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer/3",
    {
      mode: FeatureLayer.MODE_ONDEMAND,
      infoTemplate: infoTemplate,
      outFields: ['*']
    });
  var highwaysFeatureLayer = new FeatureLayer("http://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer/1",
    {
      mode: FeatureLayer.MODE_ONDEMAND,
      infoTemplate: infoTemplate,
      outFields: ['*']
    });

  map.on("load", function (){
    map.addLayer(countiesFeatureLayer);
    map.addLayer(highwaysFeatureLayer);

    var query = new Query();
    query.geometry = map.extent;
    query.spatialRelationship = Query.SPATIAL_REL_ENVELOPEINTERSECTS;
    query.returnGeometry = true;
    query.outFields = ["*"];

    countiesFeatureLayer.queryFeatures(query, function (featureSet){
      var polygon = featureSet.features[0].geometry;
      // populate the Geometry cache by calling getExtent()
      var polygonExtent = polygon.getExtent();
      console.log("polygonExtent", polygonExtent);
      console.log("polygon.cache._extent", polygon.cache._extent);

      for (var i = 0; i < featureSet.features.length; i  ) {
        var feature = featureSet.features[i];
        console.log("Polygon geometry cache, %o", feature.geometry.cache);
        feature.geometry.clearCache();
        console.log("Polygon geometry clear cache, %o", feature.geometry.cache);
        // Break out of the loop after the first result
        break;
      }
    });

    highwaysFeatureLayer.queryFeatures(query, function (featureSet){
      var line = featureSet.features[0].geometry;
      // populate the Geometry cache by calling getExtent()
      var lineExtent = line.getExtent();
      console.log("lineExtent", lineExtent);
      console.log("line.cache._extent", line.cache._extent);

      for (var i = 0; i < featureSet.features.length; i  ) {
        var feature = featureSet.features[i];
        console.log("Line geometry cache, %o", feature.geometry.cache);
        feature.geometry.clearCache();
        console.log("Line geometry clear cache, %o", feature.geometry.cache);
        // Break out of the loop after the first result
        break;
      }
    });

  });
});

require([
  "esri/geometry/Point", ... 
], function(Point, ... ) {

  polyline.addPath([new Point(10,10), new Point(20,20), new Point(30,30)]);

  polyline.addPath([[-122.68,45.53], [-122.58,45.55],  [-122.57,45.58],[-122.53,45.60]]);
  ...
});