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Class: esri/layers/Layer
Inheritance: Layer Accessor
Since: ArcGIS API 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 or raster images 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 typeData sourceData typesFeaturesLimitations
FeatureLayerArcGIS FeatureServer/MapServer, ArcGIS portal item, or client-side graphicsPoints, polylines, polygons downloaded as vector graphicsClient-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
GraphicsLayerClient-side graphicsPoints, polylines, polygons displayed as vector graphicsNo 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.
MapImageLayerArcGIS MapServer,
ArcGIS portal item
Points, polylines, polygons, rasters exported in a single imageMay 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 workspacesNo editing support
SceneLayerArcGIS SceneServer, ArcGIS portal itemPoint and multipatch geometriesCan display a large number of features on the client. Ideal for rendering 3D featuresNo 2D support; no editing
CSVLayerCSV filePoints downloaded as vector graphicsClient-side processing, popup templates, renderers with 2D and 3D symbolsMay require large download depending on the number of features
KMLLayerKML file (.kml, .kmz), ArcGIS portal itemPoints, polylines, polygons displayed as vector graphicsDisplay KML file in a map or webmapNo 3D support; requires access to utility service from ArcGIS.com or ArcGIS Enterprise
StreamLayerArcGIS StreamServerPoints downloaded as vector graphicsDownloads and updates feature locations in real timeN/A
ImageryLayerArcGIS ImageServer, ArcGIS portal itemRaster data exported as a single imageClient-side and server-side pixel filtering and rendering; popup templates; queryingN/A
GeoJSONLayerGeoJSONPoints, polylines, polygonsRenderers, labels, editing, popupsData must comply with the RFC 7946 specification which states that the coordinates are in SpatialReference WGS84
OGCFeatureLayerOGC API - FeaturesPoints, polylines, polygonsRenderers, labels, popupsData must comply with the RFC 7946 specification which states that the coordinates are in SpatialReference WGS84
GeoRSSLayerGeoRSS feedPoints, polylines, polygonsNo geometry schema; popup templatesNo 3D support; no support for renderers
MapNotesLayerArcGIS WebMap, ArcGIS portal itemPoints, polylines, polygons, textMap Notes in a webmapNo 3D support; Read-only
WMSLayerWMS service,
ArcGIS portal item
Data exported as a single imageOGC specificationN/A
BaseDynamicLayerArcGIS MapServer, WMS serviceData exported as a single imageThis class may be extended to create dynamic map layersNo 3D support; exported images cannot be cached in the browser
BuildingSceneLayerArcGIS SceneServer, ArcGIS portal itemData is organized in BuildingGroupSublayers which contain BuildingComponentSublayersVisualize complex digital models of buildings and interact with its componentsNo 2D support

Layers for providing geographic context

Layer typeData sourceData typesFeaturesLimitations
TileLayerArcGIS MapServer, ArcGIS portal itemImage tilesBetter performance for large datasets; querying featuresNo editing, client-side rendering, or popup templates; some schema limitations in 3D views.
BaseTileLayerArcGIS MapServer, ArcGIS portal itemImage tilesThis class may be extended to create custom tile layersNo editing, client-side rendering, or popup templates; some schema limitations in 3D views.
VectorTileLayerArcGIS portal itemPoints, polylines, and polygons rendered as vector tilesFeatures may be styled client-side and used as a tiled basemapNo editing, client-side rendering, or popup templates.
IntegratedMeshLayerArcGIS SceneServer, ArcGIS portal itemPoint cloud mesh integrated with imageryDisplays 3D objects with a high level of detailNo 2D support
ElevationLayerArcGIS ImageServer, ArcGIS portal itemTiled elevation mesh/surfaceRenders elevation surfaces in 3D viewsNo 2D support
BaseElevationLayerArcGIS ImageServer, ArcGIS portal itemTiled elevation mesh/surfaceThis class may be extended to create custom elevation layersNo 2D support
PointCloudLayerArcGIS SceneServer, ArcGIS portal itemPoint clouds (e.g. collected from LiDAR)Renderers; fast display of point cloudsNo 2D support
OpenStreetMapLayerOpenStreetMap tile servicesImage tilesDisplays OpenStreetMap tiled contentN/A
WMTSLayerWMTS tile services,
ArcGIS portal item
Image tilesOGC specificationN/A
WebTileLayernon-ArcGIS, non-OGC, and non-OSM tile servicesImage tilesN/ANo editing, client-side rendering, or popup templates.
BingMapsLayerBing Spatial Data Service dataImage tilesDisplays Microsoft's Bing tiled contentBing Maps key is required; three map styles are supported: road, aerial, and hybrid

Other layers

Layer typeData sourceData typesFeaturesLimitations
GroupLayerAny combination of other layer typesN/ACombines two or more layers into a single layerN/A
See also:

Property Overview

Any properties can be set, retrieved or listened to. See the Working with Properties topic.
NameTypeSummaryClass
String

Blend modes are used to blend layers together to create an interesting effect in a layer, or even to produce what seems like a new layer.

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String

The name of the class.

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Extent

The full extent of the layer.

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String

The unique ID assigned to the layer.

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String

Indicates how the layer should display in the LayerList widget.

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Boolean

Indicates whether the layer's resources have loaded.

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Error

The Error object returned if an error occurred while loading.

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String

Represents the status of a load operation.

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Object[]

A list of warnings which occurred while loading.

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Number

The opacity of the layer.

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String

The title of the layer used to identify it in places such as the Legend and LayerList widgets.

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String

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

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Boolean

Indicates if the layer is visible in the View.

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Property Details

blendMode String
Since: ArcGIS API for JavaScript 4.16

Blend modes are used to blend layers together to create an interesting effect in a layer, or even to produce what seems like a new layer. Unlike the method of using transparency which can result in a washed-out top layer, blend modes can create a variety of very vibrant and intriguing results by blending a layer with the layer(s) below it.

When blending layers, a top layer is a layer that has a blend mode applied. All layers underneath the top layer are background layers. The default blending mode is normal where the top layer is simply displayed over the background layer. While this default behavior is perfectly acceptable, the use of blend modes on layers open up a world of endless possibilities to generate creative maps.

The layers in a GroupLayer are blended together in isolation from the rest of the map.

In the following screenshots, the vintage shaded relief layer is displayed over a firefly world imagery layer. The color blend mode is applied to the vintage shaded relief and the result looks a new layer.

color-blend

Known Limitations

The following factors will affect the blend result:

  • Order of all layers
  • Layer opacity
  • Opacity of features in layers
  • Visibility of layers
  • By default, the very bottom layer in a map is drawn on a transparent background. You can change the MapView's background color.
Blend modeDescription
normalThe top layer is displayed over the background layer. The data of the top layer block the data of background layer where they overlap.
averageTakes the mathematical average of top and background layers. Result of average blend mode is often similar to the effect of setting the layer's opacity to 50%.

Lighten blend modes:

The following blend modes create lighter results than all layers. In lighten blend modes, pure black colors in the top layer become transparent allowing the background layer to show through. White in the top layer will stay unchanged. Any color that is lighter than pure black is going to lighten colors in the top layer to varying degrees all way to pure white.

Lighten blend modes can be useful when lightening dark colors of the top layer or removing black colors from the result. The plus, lighten and screen modes can be used to brighten layers that have faded or dark colors on a dark background.

Blend modeDescription
lightenCompares top and background layers and retains the lighter color in the top layer. Colors in the top layer become transparent if they are darker than the overlapping colors in the background layer allowing the background layer to show through completely. Can be thought of as the opposite of darken blend mode.
lighterColors in top and background layers are multiplied by their alphas (layer opacity and layer's data opacity. Then the resulting colors are added together. All overlapping midrange colors are lightened in the top layer. The opacity of layer and layer's data will affect the blend result.
plusColors in top and background layers are added together. All overlapping midrange colors are lightened in the top layer. This mode is also known as add or linear-dodge.
screenInverts colors of the background layer and multiplies with colors of the top layer. The resulting colors will be lighter than the original color with less contrast. Screen can produce many different levels of brightening depending on the luminosity values of the top layer. Can be thought of as the opposite of the multiply mode.
color-dodgeCreates a brighter effect by decreasing the contrast between the top and background layers, resulting in saturated mid-tones and bright highlights.

Darken blend modes:

The following blend modes create darker results than all layers. In darken blend modes, pure white in the top layer will become transparent allowing the background layer to show through. Black in the top layer will stay unchanged. Any color that is darker than pure white is going to darken a top layer to varying degrees all the way to pure black.

The multiply blend mode is often used to highlight shadows, show contrast, or accentuate an aspect of a map. For example, you can use multiply blend mode on a topographic map displayed over hillshade when you want to have your elevation show through the topographic layer. See the intro to layer blending sample.

The multiply and darken modes can be used to have dark labels of the basemap to show through top layers. See the darken blending sample.

The color-burn mode works well with colorful top and background layers since it increases saturation in mid-tones. It increases the contrast by tinting pixels in overlapping areas in top and bottom layers more towards the top layer color. Use this blend mode, when you want an effect with more contrast than multiply or darken.

The following screenshots show how the multiply blend mode used for creating a physical map of the world that shows both boundaries and elevation. multiply-blend

Blend modeDescription
darkenEmphasizes the darkest parts of overlapping layers. Colors in the top layer become transparent if they are lighter than the overlapping colors in the background layer, allowing the background layer to show through completely.
multiplyEmphasizes the darkest parts of overlapping layers by multiplying colors of the top layer and the background layer. Midrange colors from top and background layers are mixed together more evenly.
color-burnIntensifies the dark areas in all layers. It increases the contrast between top and background layers, by tinting colors in overlapping area towards the top color. To do this it inverts colors of the background layer, divides the result by colors of the top layer, then inverts the results.

Contrast blend modes:

The following blend modes create contrast by both lightening the lighter areas and darkening the darker areas in the top layer by using lightening or darkening blend modes to create the blend. The contrast blend modes will lighten the colors lighter than 50% gray ([128,128,128]), and darken the colors darker than 50% gray. 50% gray will be transparent in the top layer. Each mode can create a variety of results depending on the colors of top and background layers being blended together. The overlay blend mode makes its calculations based on the brightness of the colors in the background layer while all of the other contrast blend modes make their calculations based on the brightness of the top layer. Some of these modes are designed to simulate the effect of shining a light through the top layer, effectively projecting upon the layers beneath it.

Contrast blend modes can be used to increase the contrast and saturation to have more vibrant colors and give a punch to your layers. For example, you can duplicate a layer and set overlay blend mode on the top layer to increase the contrast and tones of your layer. You can also add a polygon layer with a white fill symbol over a dark imagery layer and apply soft-light blend mode to increase the brightness in the imagery layer.

The following screenshots show an effect of the overlay blend mode on a GraphicsLayer. The left image shows when the buffer graphics layer has the normal blend mode. As you can see, the gray color for the buffer polygon is blocking the intersecting census tracts. The right image shows when the overlay blend mode is applied to the buffer graphics layer. The overlay blend mode darkens or lightens the gray buffer polygon depending on the colors of the background layer while the census tracts layer is shining through. See this in action.

Normal blend modeOverlay blend mode
no-blendmodeoverlay-blend
Blend modeDescription
overlayUses a combination of multiply and screen modes to darken and lighten colors in the top layer with the background layer always shining through. The result is darker color values in the background layer intensify the top layer, while lighter colors in the background layer wash out overlapping areas in the top layer.
soft-lightApplies a half strength screen mode to lighter areas and and half strength multiply mode to darken areas of the top layer. You can think of the soft-light as a softer version of the overlay mode.
hard-lightMultiplies or screens the colors, depending on colors of the top layer. The effect is similar to shining a harsh spotlight on the top layer.
vivid-lightUses a combination of color-burn or color-dodge by increasing or decreasing the contrast, depending on colors in the top layer.

Component blend modes:

The following blend modes use primary color components, which are hue, saturation and luminosity to blend top and background layers. You can add a feature layer with a simple renderer over any layer and set hue, saturation, color or luminosity blend mode on this layer. With this technique, you create a brand new looking map.

The following screenshots show where the topo layer is blended with world hillshade layer with luminosity blend mode. The result is a drastically different looking map which preserves the brightness of the topo layer while adapting the hue and saturation of the hillshade layer.

color-blend

Blend modeDescription
hueCreates an effect with the hue of the top layer and the luminosity and saturation of the background layer.
saturationCreates an effect with the saturation of the top layer and the hue and luminosity of the background layer. 50% gray with no saturation in the background layer will not produce any change.
luminosityCreates effect with the luminosity of the top layer and the hue and saturation of the background layer. Can be thought of as the opposite of color blend mode.
colorCreates an effect with the hue and saturation of the top layer and the luminosity of the background layer. Can be thought of as the opposite of luminosity blend mode.

Composite blend modes:

The following blend modes can be used to mask the contents of top, background or both layers.

  • Destination modes are used to mask the data of the top layer with the data of the background layer.
  • Source modes are used to mask the data of the background layer with the data of the top layer.

The destination-in blend mode can be used to show areas of focus such as earthquakes, animal migration, or point-source pollution by revealing the underlying map, providing a bird’s eye view of the phenomenon. Check out multiple blending and groupLayer blending samples to see composite blend modes in action.

The following screenshots show feature and imagery layers on the left side on their own in the order they are drawn in the view. The imagery layer that contains land cover classification rasters. The feature layer contains 2007 county crops data. The right image shows the result of layer blending where destination-in blendMode is set on the imagery layer. As you can see, the effect is very different from the original layers. The blended result shows areas of cultivated crops only (where both imagery and feature layers overlap).

destination-in

Blend modeDescription
destination-overDestination/background layer covers the top layer. The top layer is drawn underneath the destination layer. You'll see the top layer peek through wherever the background layer is transparent or has no data.
destination-atopDestination/background layer is drawn only where it overlaps the top layer. The top layer is drawn underneath the background layer. You'll see the top layer peek through wherever the background layer is transparent or has no data.
destination-inDestination/background layer is drawn only where it overlaps with the top layer. Everything else is made transparent.
destination-outDestination/background layer is drawn where it doesn't overlap the top layer. Everything else is made transparent.
source-atopSource/top layer is drawn only where it overlaps the background layer. You will see the background layer peek through where the source layer is transparent or has no data.
source-inSource/top layer is drawn only where it overlaps with the background layer. Everything else is made transparent.
source-outSource/top layer is drawn where it doesn't overlap the background layer. Everything else is made transparent.
xorTop and background layers are made transparent where they overlap. Both layers are drawn normal everywhere else.

Invert blend modes:

The following blend modes either invert or cancel out colors depending on colors of the background layer. These blend modes look for variations between top and background layers. For example, you can use difference or exclusion blend modes on two imagery layers of forest covers to visualize how forest covers changed from one year to another.

The invert blend mode can be used to turn any light basemap into a dark basemap to accommodate those who work in low-light conditions. The following screenshots show how setting the invert blend mode set on a feature layer with a simple renderer turns the world terrain basemap into a dark themed basemap in no time.

color-blend

Blend modeDescription
differenceSubtracts the darker of the overlapping colors from the lighter color. When two pixels with the same value are subtracted, the result is black. Blending with black produces no change. Blending with white inverts the colors. This blending mode is useful for aligning layers with similar content.
exclusionSimilar to the difference blend mode, except that the resulting image is lighter overall. Overlapping areas with lighter color values are lightened, while darker overlapping color values become transparent.
minusSubtracts colors of the top layer from colors of the background layer making the blend result darker. In the case of negative values, black is displayed.
invertInverts the background colors wherever the top and background layers overlap. The invert blend mode inverts the layer similar to a photographic negative.
reflectThis blend mode creates effects as if you added shiny objects or areas of light in the layer. Black pixels in the background layer are ignored as if they were transparent.

Possible Values:"average"|"color-burn"|"color-dodge"|"color"|"darken"|"destination-atop"|"destination-in"|"destination-out"|"destination-over"|"difference"|"exclusion"|"hard-light"|"hue"|"invert"|"lighten"|"lighter"|"luminosity"|"minus"|"multiply"|"normal"|"overlay"|"plus"|"reflect"|"saturation"|"screen"|"soft-light"|"source-atop"|"source-in"|"source-out"|"vivid-light"|"xor"

Default Value:normal
See also:
declaredClass Stringreadonly inherited
Since: ArcGIS API 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;
});

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.

ValueDescription
showThe layer is visible in the table of contents.
hideThe layer is hidden in the table of contents.
hide-childrenIf 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.

ValueDescription
not-loadedThe object's resources have not loaded.
loadingThe object's resources are currently loading.
loadedThe object's resources have loaded without errors.
failedThe 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 Legend and LayerList widgets.

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"|"elevation"|"feature"|"geojson"|"geo-rss"|"graphics"|"group"|"imagery"|"imagery-tile"|"integrated-mesh"|"kml"|"map-image"|"map-notes"|"ogc-feature"|"open-street-map"|"point-cloud"|"route"|"scene"|"stream"|"tile"|"unknown"|"unsupported"|"vector-tile"|"web-tile"|"wms"|"wmts"

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

NameReturn TypeSummaryClass

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

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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.

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Boolean

Emits an event on the instance.

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Promise<Object>

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

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Promise<Layer>

Creates a new layer instance from an ArcGIS Server URL.

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Promise<Layer>

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

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Boolean

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

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Boolean

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

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Boolean

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

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Boolean

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

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Promise

Loads the resources referenced by this class.

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Object

Registers an event handler on the instance.

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Promise

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

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Method Details

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:
optional

A signal to abort the creation of the layerview.

Returns:
TypeDescription
Promise<LayerView>Resolves with a LayerView instance.
See also:
emit(type, event){Boolean}
Since: ArcGIS API 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:
TypeDescription
Booleantrue if a listener was notified
fetchAttributionData(){Promise<Object>}

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

Returns:
TypeDescription
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, SceneLayer, StreamLayer, 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.

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:
TypeDescription
Promise<Layer>Returns a promise that resolves to the new Layer instance.
Example:
// get an ArcGIS server url from a custom function
var 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);
});
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.

See also: isLayer

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:
TypeDescription
Promise<Layer>Returns a promise which resolves to the new layer instance.
Example:
Layer.fromPortalItem({
  portalItem: {  // autocasts new PortalItem()
    id: "8444e275037549c1acab02d2626daaee"
  }
}).then(function(layer){
  // add the layer to the map
  map.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:
TypeDescription
BooleanReturns true if the class supports the input event.
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:
TypeDescription
BooleanIndicates 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:
TypeDescription
BooleanIndicates 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:
TypeDescription
BooleanIndicates 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.

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:
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:
TypeDescription
PromiseResolves 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:

A event type, or an array of event types, to listen for.

listener Function

The function to call when the event is fired.

Returns:
TypeDescription
ObjectReturns an event handler with a remove() method that can be called to stop listening for the event(s).
PropertyTypeDescription
removeFunctionWhen 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);
});
when(callback, errback){Promise}
Since: ArcGIS API 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:
TypeDescription
PromiseReturns 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
var 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

NameTypeSummaryClass
{view: View,layerView: LayerView}

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

more details
more detailsLayer
{view: View,error: Error}

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

more details
more detailsLayer
{view: View,layerView: LayerView}

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

more details
more detailsLayer

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:
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:
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.

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