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Layer | API Reference | ArcGIS Maps SDK for JavaScript 4.33

ESM: import Layer from "@arcgis/core/layers/Layer.js";

CDN: const Layer = await $arcgis.import("@arcgis/core/layers/Layer.js");

Class: @arcgis/core/layers/Layer

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.

See also

• Intro to layers

• FeatureLayer
• MapImageLayer
• TileLayer
• SceneLayer
• ElevationLayer
• KnowledgeGraphLayer

Show inherited properties Hide inherited properties

declaredClass

Inherited

Property declaredClass Stringreadonly

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.

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;
});

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.

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

The Error object returned if an error occurred while loading.

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.

loaded Property loaded Booleanreadonly

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

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.

Example

// Makes the layer 50% transparent
layer.opacity = 0.5;

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 Booleanreadonly

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.

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" |"catalog" |"catalog-dynamic-group" |"catalog-footprint" |"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" |"parquet" |"point-cloud" |"route" |"scene" |"georeferenced-image" |"stream" |"tile" |"unknown" |"unsupported" |"vector-tile" |"viewshed" |"wcs" |"web-tile" |"wfs" |"wms" |"wmts" |"video" |"voxel" |"subtype-group" |"knowledge-graph" |"knowledge-graph-sublayer" |"link-chart"

uid Property uid Stringreadonly

Since: ArcGIS Maps SDK for JavaScript 4.33 Layer since 4.0, uid added at 4.33.

An automatically generated unique identifier assigned to the instance. The unique id is generated each time the application is loaded.

Since: ArcGIS Maps SDK for JavaScript 4.30 Layer since 4.0, visibilityTimeExtent added at 4.30.

Specifies a fixed time extent during which a layer should be visible. This property can be used to configure a layer that does not have time values stored in an attribute field to work with time. Once configured, the TimeSlider widget will display the layer within the set time extent. In the case that only one of the start or end date values are available, the layer remains visible indefinitely in the direction where there is no time value.

Aerial imagery can capture seasonal variations in vegetation, water bodies, and land use patterns. For example, in agricultural regions, aerial imageries taken during different growing seasons provide insights into crop health and productivity. Defining a fixed time extent on imageries from specific time periods provides temporal context and facilitates focused analysis based on specific time periods or events.

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.

Example

// The layer is no longer visible in the view
layer.visible = false;

// Watch for changes in the layer's visibility
// and set the visibility of another layer when it changes
reactiveUtils.watch(
  () => layer.visible,
  (visible) => {
    if (visible) {
      anotherLayer.visible = true;
    } else {
      anotherLayer.visible = false;
    }
  }
);

Show inherited methods Hide inherited methods

addHandles

Inherited

Method addHandles(handleOrHandles, groupKey)

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

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.

optional

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

Returns

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

The name of the event.

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 BuildingSceneLayer, CatalogLayer, ElevationLayer, FeatureLayer, GroupLayer, ImageryLayer, ImageryTileLayer, IntegratedMeshLayer, KnowledgeGraphLayer, MapImageLayer, OrientedImageryLayer, PointCloudLayer, SceneLayer, StreamLayer, SubtypeGroupLayer, TileLayer, or VideoLayer.

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

Input parameters for creating the layer.

Specification

The ArcGIS Server URL used to create the layer.

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.

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 and OrientedImageryLayer 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.

Parameters

The parameters for loading the portal item.

Specification

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.

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.

Returns

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

hasHandles

Inherited

Method hasHandles(groupKey){Boolean}

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(options){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.

Parameters

optional

Additional options.

Specification

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.

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)

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

optional

The function to call when the promise resolves.

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
});

layerview-create Event layerview-create

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

Properties

The view in which the layerView was created.

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 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

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

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 Event layerview-destroy

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

Properties

The view in which the layerView was destroyed.

The destroyed LayerView representing the layer.

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