Layer

Property Overview

Property Details

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.

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 String

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

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 Booleanreadonly

Indicates whether the layer's resources have 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.

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;

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 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"|"kml"|"line-of-sight"|"map-image"|"map-notes"|"media"|"ogc-feature"|"open-street-map"|"point-cloud"|"route"|"scene"|"georeferenced-image"|"stream"|"tile"|"unknown"|"unsupported"|"vector-tile"|"wcs"|"web-tile"|"wfs"|"wms"|"wmts"|"voxel"|"subtype-group"|"knowledge-graph"

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

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.

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.

See also

• Sample - Custom WebGL layer view

destroy()

Since: ArcGIS Maps SDK for JavaScript 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.

See also

• Map.destroy()
• WebMap.destroy()
• WebScene.destroy()
• Basemap.destroy()
• Ground.destroy()
• PortalItem.destroy()

emit(type, event){Boolean}

Since: ArcGIS Maps SDK for JavaScript 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(){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(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, 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

• isTable

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(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.

Beginning with version 4.25, CSVLayer and GeoJSONLayer can be loaded from csv and geojson portal items respectively.

Beginning with 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

• This method does not currently work with OGCFeatureServer portal items.

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

• isLayer
• isTable

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(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(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.

on(type, listener){Object}

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

Parameters

type String|String[] 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(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");

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
});

Event Overview

Event Details

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

• View.whenLayerView()

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

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

• View.whenLayerView()

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

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.