Basemap

AMD: require(["esri/Basemap"], (Basemap) => { /* code goes here */ });
ESM: import Basemap from "@arcgis/core/Basemap.js";
Class: esri/Basemap
Inheritance: Basemap Accessor
Since: ArcGIS Maps SDK for JavaScript 4.0

Overview

A basemap is a collection of layers that provide geographic context to a map or scene with data such as topographic features, road networks, buildings, and labels. These features can be represented with different styles as applicable to your application, such as streets, topographic, or imagery.

A basemap can contain both base layers, which comprise one or more tiled layers, and reference layers. Reference layers are displayed on top of the base layers, and can be used, for example, to display labels on top of terrain or streets.

In a MapView, a basemap's reference layers are limited to tiled layers, while in a SceneView they can also contain Scene Layers and be used to display 3D content. For example, a 3D basemap could include 3D objects such as buildings and trees, or labels to be rendered in 3D, either draped over the terrain in a tiled layer, or billboarded in a scene layer.

Creating a Basemap

Creates a new basemap object. Basemaps can be created from a PortalItem, from a well known basemap ID, or can be used for creating custom basemaps. These basemaps may be created from tiled services you publish to your own server, or from tiled services published by third parties.

// in this case the portalItem has to be a webmap
let basemap = new Basemap({
  portalItem: {
    id: "8dda0e7b5e2d4fafa80132d59122268c"  // WGS84 Streets Vector webmap
  }
});

// or create the basemap from a well known ID
Basemap.fromId("topo-vector");

// or create from a third party source
let basemap = new Basemap({
  baseLayers: [
    new WebTileLayer(...)
  ],
  referenceLayers: [
    new WebTileLayer(...)
  ],
});

Setting the LOD

The MapView.constraints.lods property should be specified when using a dynamic service for a basemap. Do this by either explicitly setting the lods within this property, or create the lods via the create() method on the TileInfo class. This method is used to create a new TileInfo instance with preset properties for lods. See Zoom and LODs section in MapView SDK document for more information.

// create a basemap from a dynamic mapserver
let basemap = new Basemap({
  baseLayers: [
    new MapImageLayer({
      url: "url to your dynamic MapServer",
      title: "Basemap"
    })
  ],
  title: "basemap",
  id: "basemap"
});

let map = new Map({
  basemap: basemap
});

// create a TileInfo instance using the default settings and
// pass its resulting LOD's to a MapView's constraints
// in this case, lods will match the ArcGIS Online web mercator LODs
let view = new MapView({
  container: "viewDiv",
  map: map,
  constraints: {
    lods: TileInfo.create().lods
  }
});

Waiting for Load

The when() method on the Basemap instance can be called to execute processes that may only run after the Basemap is loaded.

See also

Constructors

new Basemap(properties)
Parameter
properties Object
optional

See the properties for a list of all the properties that may be passed into the constructor.

Property Overview

Any properties can be set, retrieved or listened to. See the Working with Properties topic.
Show inherited properties Hide inherited properties
Name Type Summary Class
Collection<Layer>

A collection of tile layers that make up the basemap's features.

more details
Basemap
String

The name of the class.

more details
Accessor
String

An identifier used to refer to the basemap when referencing it elsewhere.

more details
Basemap
Boolean

Indicates whether the basemap instance has loaded.

more details
Basemap
Error

The Error object returned if an error occurred while loading.

more details
Basemap
String

Represents the status of a load operation.

more details
Basemap
Object[]

A list of warnings which occurred while loading.

more details
Basemap
PortalItem

The portal item.

more details
Basemap
Collection<Layer>

A collection of reference layers which are displayed over the base layers and can be used to display labels on top of terrain or streets.

more details
Basemap
SpatialReference

The spatial reference of the Basemap.

more details
Basemap
String

The URL pointing to an image that represents the basemap.

more details
Basemap
String

The title of the basemap.

more details
Basemap

Property Details

A collection of tile layers that make up the basemap's features.

declaredClass Stringreadonly inherited
Since: ArcGIS Maps SDK for JavaScript 4.7

The name of the class. The declared class name is formatted as esri.folder.className.

id String

An identifier used to refer to the basemap when referencing it elsewhere.

Example
let customBasemap = new Basemap({
  baseLayers: [layers],
  title: "Custom Basemap",
  id: "myBasemap"
});
loaded Booleanreadonly

Indicates whether the basemap instance has loaded. When true, all the properties of the object can be accessed.

Default Value:false
loadError Errorreadonly

The Error object returned if an error occurred while loading.

Default Value:null
loadStatus Stringreadonly

Represents the status of a load operation.

Value Description
not-loaded The object's resources have not loaded.
loading The object's resources are currently loading.
loaded The object's resources have loaded without errors.
failed The object's resources failed to load. See loadError for more details.

Possible Values:"not-loaded"|"loading"|"failed"|"loaded"

Default Value:not-loaded
loadWarnings Object[]readonly

A list of warnings which occurred while loading.

portalItem PortalItemautocast

The portal item.

referenceLayers Collection<Layer>

A collection of reference layers which are displayed over the base layers and can be used to display labels on top of terrain or streets. In a MapView, a basemap's reference layers are limited to tiled layers, while in a SceneView they can also contain Scene Layers and be used to display objects or labels in 3D.

spatialReference SpatialReferenceautocast
Since: ArcGIS Maps SDK for JavaScript 4.14

The spatial reference of the Basemap. For complete listings of supported coordinate systems, see Using spatial references.

When using an Esri basemap, the default spatial reference is Web Mercator Auxiliary Sphere.

thumbnailUrl String

The URL pointing to an image that represents the basemap. When using a custom basemap in the BasemapToggle widget, the image specified here will display in the widget. When the user clicks the image, the map's basemap will update to the basemap associated with the image.

See also
title String

The title of the basemap.

Method Overview

Show inherited methods Hide inherited methods
Name Return Type Summary Class

Adds one or more handles which are to be tied to the lifecycle of the object.

more details
Accessor

Cancels a load() operation if it is already in progress.

more details
Basemap
Basemap

Creates a deep clone of this object.

more details
Basemap

Destroys the basemap, and any associated resources, including its layers and portalItem.

more details
Basemap
Basemap

Creates a new basemap instance from a well known basemap ID.

more details
Basemap
*

Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product.

more details
Basemap
Boolean

Returns true if a named group of handles exist.

more details
Accessor
Boolean

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected).

more details
Basemap
Boolean

isRejected() may be used to verify if creating an instance of the class is rejected.

more details
Basemap
Boolean

isResolved() may be used to verify if creating an instance of the class is resolved.

more details
Basemap
Promise

Loads the resources referenced by this class.

more details
Basemap
Promise<Basemap>

Loads all the externally loadable resources associated with the basemap.

more details
Basemap

Removes a group of handles owned by the object.

more details
Accessor
Object

Converts an instance of this class to its ArcGIS portal JSON representation.

more details
Basemap
Promise

when() may be leveraged once an instance of the class is created.

more details
Basemap

Method Details

addHandles(handleOrHandles, groupKey)inherited
Since: ArcGIS Maps SDK for JavaScript 4.25

Adds one or more handles which are to be tied to the lifecycle of the object. The handles will be removed when the object is destroyed.

// Manually manage handles
const handle = reactiveUtils.when(
  () => !view.updating,
  () => {
    wkidSelect.disabled = false;
  },
  { once: true }
);

this.addHandles(handle);

// Destroy the object
this.destroy();
Parameters
handleOrHandles WatchHandle|WatchHandle[]

Handles marked for removal once the object is destroyed.

groupKey *
optional

Key identifying the group to which the handles should be added. All the handles in the group can later be removed with Accessor.removeHandles(). If no key is provided the handles are added to a default group.

cancelLoad()

Cancels a load() operation if it is already in progress.

clone(){Basemap}

Creates a deep clone of this object.

Returns
Type Description
Basemap A deep clone of the Basemap instance that invoked this method.
destroy()
Since: ArcGIS Maps SDK for JavaScript 4.17

Destroys the basemap, and any associated resources, including its layers and portalItem. These can no longer be used once the basemap has been destroyed. To prevent these objects from being destroyed, remove them from the basemap before calling destroy().

// prevent the layers from being destroyed by removing them from the basemap
const baseLayers = basemap.baseLayers.removeAll();
const referenceLayers = basemap.referenceLayers.removeAll();

// unset portalItem from the basemap so that it is not destroyed
const portalItem = basemap.portalItem;
basemap.portalItem = null;

// destroy the basemap and any remaining associated resources
basemap.destroy();
See also
fromId(id){Basemap}static

Creates a new basemap instance from a well known basemap ID. See Map.basemap for a list of possible values.

Parameter
id String

The basemap ID.

Returns
Type Description
Basemap A new Basemap instance.
Examples
let streetsBasemap = Basemap.fromId("streets-vector");
let nightBasemap = Basemap.fromId("streets-night-vector");
fromJSON(json){*}static

Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product. The object passed into the input json parameter often comes from a response to a query operation in the REST API or a toJSON() method from another ArcGIS product. See the Using fromJSON() topic in the Guide for details and examples of when and how to use this function.

Parameter
json Object

A JSON representation of the instance in the ArcGIS format. See the ArcGIS REST API documentation for examples of the structure of various input JSON objects.

Returns
Type Description
* Returns a new instance of this class.
hasHandles(groupKey){Boolean}inherited
Since: ArcGIS Maps SDK for JavaScript 4.25

Returns true if a named group of handles exist.

Parameter
groupKey *
optional

A group key.

Returns
Type Description
Boolean Returns true if a named group of handles exist.
Example
// Remove a named group of handles if they exist.
if (obj.hasHandles("watch-view-updates")) {
  obj.removeHandles("watch-view-updates");
}
isFulfilled(){Boolean}

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected). If it is fulfilled, true will be returned.

Returns
Type Description
Boolean Indicates whether creating an instance of the class has been fulfilled (either resolved or rejected).
isRejected(){Boolean}

isRejected() may be used to verify if creating an instance of the class is rejected. If it is rejected, true will be returned.

Returns
Type Description
Boolean Indicates whether creating an instance of the class has been rejected.
isResolved(){Boolean}

isResolved() may be used to verify if creating an instance of the class is resolved. If it is resolved, true will be returned.

Returns
Type Description
Boolean Indicates whether creating an instance of the class has been resolved.
load(signal){Promise}

Loads the resources referenced by this class. This method automatically executes for a View and all of the resources it references in Map if the view is constructed with a map instance.

This method must be called by the developer when accessing a resource that will not be loaded in a View.

The load() method only triggers the loading of the resource the first time it is called. The subsequent calls return the same promise.

It's possible to provide a signal to stop being interested into a Loadable instance load status. When the signal is aborted, the instance does not stop its loading process, only cancelLoad can abort it.

Parameter
signal AbortSignal
optional

Signal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named AbortError when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.

Returns
Type Description
Promise Resolves when the resources have loaded.
loadAll(){Promise<Basemap>}
Since: ArcGIS Maps SDK for JavaScript 4.9

Loads all the externally loadable resources associated with the basemap. For the basemap this will load all the base layers and reference layers.

Returns
Type Description
Promise<Basemap> Resolves when all the loadable resources have been loaded. Rejects if at least one of the loadable resources failed to load.
See also
Example
// Load all resources but ignore if one or more of them failed to load
basemap.loadAll()
  .catch(function(error) {
    // Ignore any failed resources
  })
  .then(function() {
    console.log("All loaded");
  });
removeHandles(groupKey)inherited
Since: ArcGIS Maps SDK for JavaScript 4.25

Removes a group of handles owned by the object.

Parameter
groupKey *
optional

A group key or an array or collection of group keys to remove.

Example
obj.removeHandles(); // removes handles from default group

obj.removeHandles("handle-group");
obj.removeHandles("other-handle-group");
toJSON(){Object}

Converts an instance of this class to its ArcGIS portal JSON representation. See the Using fromJSON() guide topic for more information.

Returns
Type Description
Object The ArcGIS portal JSON representation of an instance of this class.
when(callback, errback){Promise}
Since: ArcGIS Maps SDK for JavaScript 4.6

when() may be leveraged once an instance of the class is created. This method takes two input parameters: a callback function and an errback function. The callback executes when the instance of the class loads. The errback executes if the instance of the class fails to load.

Parameters
callback Function
optional

The function to call when the promise resolves.

errback Function
optional

The function to execute when the promise fails.

Returns
Type Description
Promise Returns a new promise for the result of callback that may be used to chain additional functions.
Example
// Although this example uses MapView, any class instance that is a promise may use when() in the same way
let view = new MapView();
view.when(function(){
  // This function will execute once the promise is resolved
}, function(error){
  // This function will execute if the promise is rejected due to an error
});

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