Layer

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

The layer is the most fundamental component of a Map. It is a collection of spatial data in the form of vector graphics, raster images, or 3D objects that represent real-world phenomena. Layers may contain discrete features that store vector data or continuous cells/pixels that store raster data.

In the case of vector-based layers, such as FeatureLayer and GraphicsLayer, each feature contained in the layer has a Geometry that allows it to be rendered as a Graphic with spatial context on the view. Features within the layer also contain data attributes that provide additional information, which may be viewed in popup windows and used for rendering the layer.

To create a layer you must use one of the subclasses of Layer or call the Layer.fromPortalItem() method. A few examples of layers include the following:

  • Roads and highways may be represented using linear features in a FeatureLayer
  • Land parcels can be displayed as polygons in a MapImageLayer
  • Satellite imagery may be displayed as tiled images in a TileLayer

Multiple layers may be added to the same map and overlaid on top of one another for visualization and analytical purposes. See Map for additional information regarding how to add layers to a map. Layers are rendered in the View with a LayerView.

In a broad sense, layers can be used for the following purposes:

  • Displaying location for geographic context
  • Querying data
  • Displaying categorical and/or numeric data
  • Analytics

All layer types inherit from Layer. To learn more about each layer type, comparing and contrasting their data sources and capabilities, see the table below.

Layers for querying, visualizing, analyzing data

Layer type Data source Data types Features Limitations
FeatureLayer ArcGIS FeatureServer/MapServer, ArcGIS portal item, or client-side graphics Points, polylines, polygons downloaded as vector graphics Client-side processing, popup templates, renderers with 2D and 3D symbols, querying, editing (in a future release) Limited number of features for display; may require large download depending on number of features
GraphicsLayer Client-side graphics Points, polylines, polygons displayed as vector graphics No geometry schema. Points, polylines and polygons may be stored in a single layer. No renderer nor popup templates; visualization and popup templates are handled on a graphic-by-graphic basis.
MapImageLayer ArcGIS MapServer, ArcGIS portal item Points, polylines, polygons, rasters exported in a single image May contain nested sublayers. Server-side processing of renderers, popup templates, opacity, and labels for fast display of many features. May be used to display, query, and join data in registered workspaces No editing support
SceneLayer ArcGIS SceneServer, ArcGIS portal item Point and multipatch geometries Can display a large number of features on the client. Ideal for rendering 3D features No 2D support; editing via associated feature layer
CSVLayer CSV file Points downloaded as vector graphics Client-side processing, popup templates, renderers with 2D and 3D symbols May require large download depending on the number of features
KMLLayer KML file (.kml, .kmz), ArcGIS portal item Points, polylines, polygons displayed as vector graphics Display KML file in a map or webmap No 3D support; requires access to utility service from ArcGIS.com or ArcGIS Enterprise
StreamLayer ArcGIS StreamServer Points downloaded as vector graphics Downloads and updates feature locations in real time N/A
ImageryLayer ArcGIS ImageServer, ArcGIS portal item Raster data exported as a single image Client-side and server-side pixel filtering and rendering; popup templates; querying N/A
ImageryTileLayer ArcGIS ImageServer, ArcGIS portal item Raster data exported as a single image Client-side rendering; popup templates N/A
GeoJSONLayer GeoJSON Points, polylines, polygons Renderers, labels, editing, popups Data must comply with the RFC 7946 specification which states that the coordinates are in SpatialReference WGS84
OGCFeatureLayer OGC API - Features Points, polylines, polygons Renderers, labels, popups Data must comply with the RFC 7946 specification which states that the coordinates are in SpatialReference WGS84
GeoRSSLayer GeoRSS feed Points, polylines, polygons No geometry schema; popup templates No 3D support; no support for renderers
DimensionLayer ArcGIS WebScene DimensionAnalysis Client-side length dimensions No 2D support
LineOfSightLayer ArcGIS WebScene LineOfSightAnalysis Observer and targets for line of sight analyses No 2D support
MapNotesLayer ArcGIS WebMap, ArcGIS portal item Points, polylines, polygons, text Map Notes in a webmap No 3D support; Read-only
WCSLayer WCS service Raster data exported as a single image OGC specification N/A
WFSLayer WFS service, ArcGIS portal item Points, multipoints, lines, polygons OGC specification Data must be GeoJSON format, only support version 2.0.0
WMSLayer WMS service, ArcGIS portal item Data exported as a single image OGC specification N/A
BaseDynamicLayer ArcGIS MapServer, WMS service Data exported as a single image This class may be extended to create dynamic map layers No 3D support; exported images cannot be cached in the browser
BuildingSceneLayer ArcGIS SceneServer, ArcGIS portal item Data is organized in BuildingGroupSublayers which contain BuildingComponentSublayers Visualize complex digital models of buildings and interact with its components No 2D support
SubtypeGroupLayer ArcGIS FeatureServer/MapServer, ArcGIS portal item Points, polylines, polygons downloaded as vector graphics Contains a sublayer for each subtype in the feature service; each sublayer can be configured individually with its own renderer, popup, and labels No 3D support; no editing support at the sublayer level
KnowledgeGraphLayer ArcGIS KnowledgeGraphService Data is organized in spatial and non-spatial sublayers. Spatial sublayers contain points, multipoints, lines and polygons Contains a sublayer for each named type in the layer; each sublayer can be queried; spatial sublayers can be configured individually with their own renderer, popup, and labels Can only be added to Map instance. Not a portal item, cannot be added to WebMap or MapViewer. Requires ArcGIS Enterprise 11.1

Layers for providing geographic context

Layer type Data source Data types Features Limitations
TileLayer ArcGIS MapServer, ArcGIS portal item Image tiles Better performance for large datasets; querying features No editing, client-side rendering, or popup templates; some schema limitations in 3D views.
BaseTileLayer ArcGIS MapServer, ArcGIS portal item Image tiles This class may be extended to create custom tile layers No editing, client-side rendering, or popup templates; some schema limitations in 3D views.
VectorTileLayer ArcGIS portal item Points, polylines, and polygons rendered as vector tiles Features may be styled client-side and used as a tiled basemap No editing, client-side rendering, or popup templates.
IntegratedMeshLayer or IntegratedMesh3DTilesLayer ArcGIS SceneServer, ArcGIS portal item triangulated mesh with texture Displays 3D objects with a high level of detail No 2D support
VoxelLayer ArcGIS SceneServer, ArcGIS portal item multidimensional voxel cubes Displays multidimensional volumetric phenomena (e.g. underground models) No 2D support
ElevationLayer ArcGIS ImageServer, ArcGIS portal item Tiled elevation mesh/surface Renders elevation surfaces in 3D views No 2D support
BaseElevationLayer ArcGIS ImageServer, ArcGIS portal item Tiled elevation mesh/surface This class may be extended to create custom elevation layers No 2D support
PointCloudLayer ArcGIS SceneServer, ArcGIS portal item Point clouds (e.g. collected from LiDAR) Renderers; fast display of point clouds No 2D support
OpenStreetMapLayer OpenStreetMap tile services Image tiles Displays OpenStreetMap tiled content N/A
WMTSLayer WMTS tile services, ArcGIS portal item Image tiles OGC specification N/A
WebTileLayer non-ArcGIS, non-OGC, and non-OSM tile services Image tiles N/A No editing, client-side rendering, or popup templates.
BingMapsLayer Bing Spatial Data Service data Image tiles Displays Microsoft's Bing tiled content Bing Maps key is required; three map styles are supported: road, aerial, and hybrid
MediaLayer HTMLVideoElement, HTMLImageElement, or HTMLCanvasElement Image/video element Displays image and video elements in the map at specified geographic locations GIF/APNG not currently supported

Other layers

Layer type Data source Data types Features Limitations
GroupLayer Any combination of other layer types N/A Combines two or more layers into a single layer N/A
See also

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
String

The name of the class.

Accessor
Extent

The full extent of the layer.

Layer
String

The unique ID assigned to the layer.

Layer
String

Indicates how the layer should display in the LayerList widget.

Layer
Boolean

Indicates whether the layer's resources have loaded.

Layer
Error

The Error object returned if an error occurred while loading.

Layer
String

Represents the status of a load operation.

Layer
Object[]

A list of warnings which occurred while loading.

Layer
Number

The opacity of the layer.

Layer
Map|Basemap|Ground|GroupLayer

The parent to which the layer belongs.

Layer
Boolean

When true, the layer can be persisted.

Layer
String

The title of the layer used to identify it in places such as the LayerList widget.

Layer
String

The layer type provides a convenient way to check the type of the layer without the need to import specific layer modules.

Layer
Boolean

Indicates if the layer is visible in the View.

Layer

Property Details

declaredClass

Inherited
Property
declaredClass Stringreadonly
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.7 Accessor since 4.0, declaredClass added at 4.7.

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

fullExtent

Property
fullExtent Extentautocast

The full extent of the layer. By default, this is worldwide. This property may be used to set the extent of the view to match a layer's extent so that its features appear to fill the view. See the sample snippet below.

Example
// Once the layer loads, set the view's extent to the layer's fullextent
layer.when(function(){
  view.extent = layer.fullExtent;
});

id

Property
id String

The unique ID assigned to the layer. If not set by the developer, it is automatically generated when the layer is loaded.

listMode

Property
listMode String

Indicates how the layer should display in the LayerList widget. The possible values are listed below.

Value Description
show The layer is visible in the table of contents.
hide The layer is hidden in the table of contents.
hide-children If the layer is a GroupLayer, BuildingSceneLayer, KMLLayer, MapImageLayer, TileLayer or WMSLayer, hide the children layers from the table of contents.

Possible Values:"show"|"hide"|"hide-children"

Default Value:"show"

loaded

Property
loaded Booleanreadonly

Indicates whether the layer's resources have loaded. When true, all the properties of the object can be accessed.

Default Value:false

loadError

Property
loadError Errorreadonly

The Error object returned if an error occurred while loading.

Default Value:null

loadStatus

Property
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

Property
loadWarnings Object[]readonly

A list of warnings which occurred while loading.

opacity

Property
opacity Number

The opacity of the layer. This value can range between 1 and 0, where 0 is 100 percent transparent and 1 is completely opaque.

Default Value:1
Example
// Makes the layer 50% transparent
layer.opacity = 0.5;

parent

Property
parent Map|Basemap|Ground|GroupLayer
Since: ArcGIS Maps SDK for JavaScript 4.27 Layer since 4.0, parent added at 4.27.

The parent to which the layer belongs.

persistenceEnabled

Property
persistenceEnabled Boolean
Since: ArcGIS Maps SDK for JavaScript 4.28 Layer since 4.0, persistenceEnabled added at 4.28.

When true, the layer can be persisted. This property only has an effect for layers that are part of the WebMap or WebScene spec.

Default Value:false

title

Property
title String

The title of the layer used to identify it in places such as the LayerList widget.

If the layer is loaded from a portal item, the title of the portal item will be used. If a layer is loaded as part of a webmap or a webscene, then the title of the layer as stored in the webmap/webscene will be used.

type

Property
type Stringreadonly

The layer type provides a convenient way to check the type of the layer without the need to import specific layer modules.

Possible Values:"base-dynamic"|"base-elevation"|"base-tile"|"bing-maps"|"building-scene"|"csv"|"dimension"|"elevation"|"feature"|"geojson"|"geo-rss"|"graphics"|"group"|"imagery"|"imagery-tile"|"integrated-mesh"|"integrated-mesh-3dtiles"|"kml"|"line-of-sight"|"map-image"|"map-notes"|"media"|"ogc-feature"|"open-street-map"|"oriented-imagery"|"point-cloud"|"route"|"scene"|"georeferenced-image"|"stream"|"tile"|"unknown"|"unsupported"|"vector-tile"|"wcs"|"web-tile"|"wfs"|"wms"|"wmts"|"voxel"|"subtype-group"|"knowledge-graph"|"knowledge-graph-sublayer"

visible

Property
visible Boolean

Indicates if the layer is visible in the View. When false, the layer may still be added to a Map instance that is referenced in a view, but its features will not be visible in the view.

Default Value:true
Example
// The layer is no longer visible in the view
layer.visible = false;

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.

Accessor

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

Layer
Promise<LayerView>

Called by the views, such as MapView and SceneView, when the layer is added to the Map.layers collection and a layer view must be created for it.

Layer

Destroys the layer and any associated resources (including its portalItem, if it is a property on the layer).

Layer
Boolean

Emits an event on the instance.

Layer
Promise<object>

Fetches custom attribution data for the layer when it becomes available.

Layer
Promise<Layer>

Creates a new layer instance from an ArcGIS Server URL.

Layer
Promise<Layer>

Creates a new layer instance of the appropriate layer class from an ArcGIS Online or ArcGIS Enterprise portal item.

Layer
Boolean

Indicates whether there is an event listener on the instance that matches the provided event name.

Layer
Boolean

Returns true if a named group of handles exist.

Accessor
Boolean

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

Layer
Boolean

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

Layer
Boolean

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

Layer
Promise

Loads the resources referenced by this class.

Layer
Object

Registers an event handler on the instance.

Layer

Removes a group of handles owned by the object.

Accessor
Promise

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

Layer

Method Details

addHandles

Inherited
Method
addHandles(handleOrHandles, groupKey)
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, addHandles added at 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

Method
cancelLoad()

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

createLayerView

Method
createLayerView(view, options){Promise<LayerView>}

Called by the views, such as MapView and SceneView, when the layer is added to the Map.layers collection and a layer view must be created for it. This method is used internally and there is no use case for invoking it directly.

Parameters
view *

The parent view.

options Object
optional

An object specifying additional options. See the object specification table below for the required properties of this object.

Specification
signal AbortSignal
optional

A signal to abort the creation of the layerview.

Returns
Type Description
Promise<LayerView> Resolves with a LayerView instance.

destroy

Method
destroy()
Since: ArcGIS Maps SDK for JavaScript 4.17 Layer since 4.0, destroy added at 4.17.

Destroys the layer and any associated resources (including its portalItem, if it is a property on the layer). The layer can no longer be used once it has been destroyed.

The destroyed layer will be removed from its parent object like Map, WebMap, WebScene, Basemap, Ground, or GroupLayer.

emit

Method
emit(type, event){Boolean}
Since: ArcGIS Maps SDK for JavaScript 4.5 Layer since 4.0, emit added at 4.5.

Emits an event on the instance. This method should only be used when creating subclasses of this class.

Parameters
type String

The name of the event.

event Object
optional

The event payload.

Returns
Type Description
Boolean true if a listener was notified

fetchAttributionData

Method
fetchAttributionData(){Promise<object>}

Fetches custom attribution data for the layer when it becomes available.

Returns
Type Description
Promise<object> Resolves to an object containing custom attribution data for the layer.

fromArcGISServerUrl

Method
fromArcGISServerUrl(params){Promise<Layer>}static

Creates a new layer instance from an ArcGIS Server URL. Depending on the URL, the returned layer type may be a FeatureLayer, TileLayer, MapImageLayer, ImageryLayer, ImageryTileLayer, SceneLayer, StreamLayer, IntegratedMeshLayer, IntegratedMesh3DTilesLayer, PointCloudLayer, BuildingSceneLayer, ElevationLayer or GroupLayer.

This is useful when you work with various ArcGIS Server URLs, but you don't necessarily know which layer type(s) they create. This method creates the appropriate layer type for you. In case of a feature service or a scene service, when the URL points to the service and the service has multiple layers, the returned promise will resolve to a GroupLayer.

Beginning with version 4.17, it is possible to load tables from hosted feature services. This only applies to feature layers, and will successfully load if FeatureLayer.isTable returns true.

The following table details what is returned when loading specific URL types.

URL Returns
Feature service with one layer FeatureLayer where isTable returns false.
Feature service with one table FeatureLayer where isTable returns true.
Feature service with more than one layer(s)/table(s) GroupLayer with layers and tables.
Layers with type other than "Feature Layer" are discarded, e.g. Utility Network Layers N/A
Parameters
Specification
params Object

Input parameters for creating the layer.

Specification
url String

The ArcGIS Server URL used to create the layer.

properties Object
optional

Set any of the layer's properties here for constructing the layer instance (e.g. popupTemplate, renderer, etc.).

Returns
Type Description
Promise<Layer> Returns a promise that resolves to the new Layer instance.
See also
Examples
// This snippet shows how to add a feature layer from an ArcGIS Server URL
// Get an ArcGIS Server URL from a custom function
const arcgisUrl = getLayerUrl();

Layer.fromArcGISServerUrl({
  url: arcgisUrl,
  properties: {
    // set any layer properties here
    popupTemplate: new PopupTemplate()
  }
}).then(function(layer){
  // add the layer to the map
  map.add(layer);
});
// This snippet shows how to add a table from an ArcGIS Server URL
// Get an ArcGIS Server URL from a custom function
const arcgisUrl = getLayerUrl();

Layer.fromArcGISServerUrl({
  url: arcgisUrl
}).then(function(layer){
  // Load the table before it can be used
  layer.load().then(function() {
    // Check that it is the right type
    if (layer.isTable) {
      // Add table to map's tables collection
      map.tables.add(layer);
    }
  });
});

fromPortalItem

Method
fromPortalItem(params){Promise<Layer>}static

Creates a new layer instance of the appropriate layer class from an ArcGIS Online or ArcGIS Enterprise portal item. If the item points to a feature service with multiple layers, then a GroupLayer is created. If the item points to a service with a single layer, then it resolves to a layer of the same type of class as the service.

Note

  • At version 4.29, MediaLayer can be loaded from portal items.
  • At version 4.28, GroupLayer can be loaded from portal items.
  • At version 4.25, CSVLayer and GeoJSONLayer can be loaded from CSV and GeoJSON portal items respectively.
  • At version 4.17, it is possible to load tables from feature service items hosted in ArcGIS Online and ArcGIS Enterprise. This only applies to feature layers, and will successfully load if FeatureLayer.isTable returns true.

The following table details what is returned when loading specific item types.

Item(s) Returns
Feature service with one layer FeatureLayer where isTable returns false.
Feature service with one table FeatureLayer where isTable returns true.
Feature service with more than one layer(s)/table(s) GroupLayer with layers and tables.
Feature collection with one layer FeatureLayer where isTable returns false.
Feature collection with one table FeatureLayer where isTable returns true.
Feature collection with more than one layer(s)/table(s) GroupLayer with layers and tables.

Known Limitations

Parameters
params Object

The parameters for loading the portal item.

Specification
portalItem PortalItem

The object representing an ArcGIS Online or ArcGIS Enterprise portal item from which to load the layer.

Returns
Type Description
Promise<Layer> Returns a promise which resolves to the new layer instance.
See also
Examples
// Create a layer from a specified portal item and add to the map
Layer.fromPortalItem({
  portalItem: {  // autocasts new PortalItem()
    id: "8444e275037549c1acab02d2626daaee"
  }
}).then(function(layer){
  // add the layer to the map
  map.add(layer);
});
// Create a table from a specified portal item and add it to the map's tables collection
Layer.fromPortalItem({
  portalItem: { // autocasts new PortalItem()
    id: "123f4410054b43d7a0bacc1533ceb8dc" // This is a hosted table stored in a feature service
  }
}).then(function(layer) {
  // Necessary to load the table in order for it to be read correctly
  layer.load().then(function() {
    // Confirm this reads as a table
    if (layer.isTable) {
      // Add the new table to the map's table collection
      map.tables.add(layer);
    }
  });
});

hasEventListener

Method
hasEventListener(type){Boolean}

Indicates whether there is an event listener on the instance that matches the provided event name.

Parameter
type String

The name of the event.

Returns
Type Description
Boolean Returns true if the class supports the input event.

hasHandles

Inherited
Method
hasHandles(groupKey){Boolean}
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, hasHandles added at 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

Method
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

Method
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

Method
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

Method
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.

on

Method
on(type, listener){Object}

Registers an event handler on the instance. Call this method to hook an event with a listener.

Parameters

An event or an array of events to listen for.

listener Function

The function to call when the event fires.

Returns
Type Description
Object Returns an event handler with a remove() method that should be called to stop listening for the event(s).
Property Type Description
remove Function When called, removes the listener from the event.
Example
view.on("click", function(event){
  // event is the event handle returned after the event fires.
  console.log(event.mapPoint);
});

removeHandles

Inherited
Method
removeHandles(groupKey)
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, removeHandles added at 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");

when

Method
when(callback, errback){Promise}
Since: ArcGIS Maps SDK for JavaScript 4.6 Layer since 4.0, when added at 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
});

Event Overview

Name Type Summary Class
{view: View,layerView: LayerView}

Fires after the layer's LayerView is created and rendered in a view.

Layer
{view: View,error: Error}

Fires when an error emits during the creation of a LayerView after a layer has been added to the map.

Layer
{view: View,layerView: LayerView}

Fires after the layer's LayerView is destroyed and no longer renders in a view.

Layer

Event Details

layerview-create

Event
layerview-create

Fires after the layer's LayerView is created and rendered in a view.

Properties
view View

The view in which the layerView was created.

layerView LayerView

The LayerView rendered in the view representing the layer in layer.

See also
Example
// This function will fire each time a layer view is created for this
// particular view.
layer.on("layerview-create", function(event){
  // The LayerView for the layer that emitted this event
  event.layerView;
});

layerview-create-error

Event
layerview-create-error

Fires when an error emits during the creation of a LayerView after a layer has been added to the map.

Properties
view View

The view that failed to create a layerview for the layer emitting this event.

error Error

An error object describing why the layer view failed to create.

See also
Example
// This function fires when an error occurs during the creation of the layer's layerview
layer.on("layerview-create-error", function(event) {
  console.error("LayerView failed to create for layer with the id: ", layer.id, " in this view: ", event.view);
});

layerview-destroy

Event
layerview-destroy

Fires after the layer's LayerView is destroyed and no longer renders in a view.

Properties
view View

The view in which the layerView was destroyed.

layerView LayerView

The destroyed LayerView representing the layer.

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