WebMap

// Find a layer with title "US Counties"
const foundLayer = map.allLayers.find(function(layer) {
 return layer.title === "US Counties";
});

// Create a filtered collection of the non-group layers
const nonGroupLayers = map.allLayers.filter(function(layer) {
 return !foundLayer.layers;
});

// Listen for any layer being added or removed in the Map
map.allLayers.on("change", function(event) {
 console.log("Layer added: ", event.added);
 console.log("Layer removed: ", event.removed);
 console.log("Layer moved: ", event.moved);
});

// Watching for changes to the visible layers in the Map
reactiveUtils.watch(
  () => view.map.allLayers.filter((layer) => layer.visible),
  (newVisibleLayers, oldVisibleLayers) => {
    const added = newVisibleLayers.filter(
      (layer) => !oldVisibleLayers.includes(layer)
    );
    const removed = oldVisibleLayers.filter(
      (layer) => !newVisibleLayers.includes(layer)
    );
    added.forEach((layer) => console.log(layer.title, "is visible"));
    removed.forEach((layer) => console.log(layer.title, "is not visible"));
  }
);

// A feature layer where isTable = true.
const foundTable = map.allTables.find(function(table) {
  // Find a table with title "US Counties"
  return table.title === "US Counties";
});

// create the basemap from a string id representing the basemap style
const map = new Map({
  basemap: "osm/blueprint"
});

// create the basemap from a BasemapStyle object
const map = new Map({
 basemap: {
  style: {
   id:  "arcgis/outdoor",
   language: "es" // place labels will be displayed in spanish
  }
 }
});

// Set the basemap from a string ID in the constructor
const map = new Map({
  basemap: "dark-gray-3d"
});

// Set the basemap after the map instance is created
map.basemap = "topo-3d";

// Create a VectorTileLayer from a style URL
const mapBaseLayer = new VectorTileLayer({
  url: "https://arcgis.com/sharing/rest/content/items/b5676525747f499687f12746441101ef/resources/styles/root.json"
});

// Create a Basemap with the VectorTileLayer
const customBasemap = new Basemap({
  baseLayers: [mapBaseLayer],
  title: "Terrain"
});

// Set the basemap to the customBasemap
const map = new Map({
  basemap: customBasemap
});

// Use the world elevation service
const map = new Map({
  basemap: "topo-vector",
  ground: "world-elevation"
});

// Create a map with the world elevation layer overlaid by a custom elevation layer
const worldElevation = new ElevationLayer({
  url: "//elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer"
});
const customElevation = new ElevationLayer({
  url: "https://my.server.com/arcgis/rest/service/MyElevationService/ImageServer"
});
const map = new Map({
  basemap: "topo-vector",
  ground: new Ground({
   layers: [ worldElevation, customElevation ]
  })
});

// Add layers in the constructor of Map using an array
let fl = new FeatureLayer(url);
let gl = new GraphicsLayer();
let map = new Map({
  layers: [fl, gl]
});

// Add layers using add()
map.addMany([fl, gl]);

// Add layers using layers collection
map.layers.addMany([fl, gl]);

// Add layers using layers collection's push method
map.layers.push(fl, gl);

// This snippet shows how to add a table to a map's table collection.

// FeatureLayer.isTable = false
const featureLayer = new FeatureLayer({
  url: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/SF311/FeatureServer/0"
});

// FeatureLayer.isTable = true
const table = new FeatureLayer({
  url: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/SF311/FeatureServer/1"
});

// Add featureLayer to the map
map.add(featureLayer);

// In order for the table to be stored within
// the map's table collection, load it and confirm it is the right type.

table.load().then(() => {
  // Add the table to the collection
  map.tables.add(table);
  console.log("Table is added to map's table collection");
});

// This snippet shows how to persist a table to an existing web map

// FeatureLayer.isTable = true
const table = new FeatureLayer({
  url: "https://services.arcgis.com/V6ZHFr6zdgNZuVG0/arcgis/rest/services/Crash_details_table/FeatureServer/0"
});

// Create Webmap instance
const webmap = new WebMap({
  portalItem: {
    id: webmapId
  }
});

// When web map is ready, load the table and add it to the web map
webmap.when(() => {
  table.load().then(() => {
    console.log("Adding table");
    // Add table to the webmap's table collection
    webmap.tables.add(table);
  });
});

// Call updateFrom on webmap and pass in the existing view
webmap.updateFrom(view).then(() => {
  // Call saveAs (or save) on the web map
  webmap.saveAs({
    // autocasts as new PortalItem()
    title: "New WebMap"
  });
});

// This snippet shows how to add an in-memory table to a map

// Create the array of objects containing field info
const fields = [{
  name: "ObjectID",
  alias: "ObjectID",
  type: "oid"
},
{
  name: "tree_type",
  alias: "Tree type",
  type: "string"
},
{
  name: "species",
  alias: "Species",
  type: "string"
}];

// Create the array of graphics holding attribute info
const graphics = [{
  attributes: {
    "tree_type": "deciduous",
    "species": "maple",
    "ObjectID": 2
  }
}, {
  attributes: {
    "tree_type": "coniferous",
    "species": "pine",
    "ObjectID": 3
  }
}];

// Create the feature layer (feature collection) table
const table = new FeatureLayer({
  fields: fields,
  objectIdField: "ObjectID",
  source: graphics
});

// Check when map is ready and load the table
map.when(() => {
  table.load().then(() => {
    console.log("Adding table");
    map.tables.add(table);
  });
});

webmap.updateFrom(view)
  .then(function() {
    return webmap.save();
  })
  // thumbnail will be updated based on current extent of webmap
  .then(function(portalItem) {
    console.log("Saved to portal", portalItem.id);
  })
  .catch(function(error) {
    console.error("Error saving to portal", error);
  });