Property Overview

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.

Known Limitations

• The blendMode is not supported in 3D SceneViews.
• The blendMode is not supported in printing and in legend.

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.

Read more

Blend mode	Description
normal	The top layer is displayed over the background layer. The data of the top layer block the data of background layer where they overlap.
average	Takes 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 mode	Description
lighten	Compares 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.
lighter	Colors 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.
plus	Colors 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.
screen	Inverts 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-dodge	Creates 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.

Blend mode	Description
darken	Emphasizes 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.
multiply	Emphasizes 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-burn	Intensifies 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 mode	Overlay blend mode

Blend mode	Description
overlay	Uses 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-light	Applies 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-light	Multiplies 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-light	Uses 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.

Blend mode	Description
hue	Creates an effect with the hue of the top layer and the luminosity and saturation of the background layer.
saturation	Creates 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.
luminosity	Creates 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.
color	Creates 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).

Blend mode	Description
destination-over	Destination/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-atop	Destination/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-in	Destination/background layer is drawn only where it overlaps with the top layer. Everything else is made transparent.
destination-out	Destination/background layer is drawn where it doesn't overlap the top layer. Everything else is made transparent.
source-atop	Source/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-in	Source/top layer is drawn only where it overlaps with the background layer. Everything else is made transparent.
source-out	Source/top layer is drawn where it doesn't overlap the background layer. Everything else is made transparent.
xor	Top 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.

Blend mode	Description
difference	Subtracts 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.
exclusion	Similar 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.
minus	Subtracts 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.
invert	Inverts the background colors wherever the top and background layers overlap. The invert blend mode inverts the layer similar to a photographic negative.
reflect	This 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:

• Layer blending samples

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.

effect Effect

Since: ArcGIS API for JavaScript 4.18

Effect provides various filter functions that can be performed on the layer to achieve different visual effects similar to how image filters work. This powerful capability allows you to apply css filter-like functions to layers to create custom visual effects to enhance the cartographic quality of your maps. This is done by applying the desired effect to the layer's effect property as a string or an array of objects to set scale dependent effects.

Known Limitations

• The effect is not supported in 3D SceneViews.
• The effect is not supported in printing and in legend.

Default Value:null

See also:

• More information on how to set effect

• Layer and layer view effect samples

Examples:

// the following effect will be applied to the layer at all scales
// brightness will be applied first, then hue-rotate followed by contrast
// changing order of the effects will change the final result
layer.effect = "brightness(5) hue-rotate(270deg) contrast(200%)";

// set a scale dependent bloom effect on the layer
layer.effect = [
  {
    scale: 36978595,
    value: "drop-shadow(3px, 3px, 4px)"
  },
  {
    scale: 18489297,
    value: "drop-shadow(2px, 2px, 3px)"
  },
  {
    scale: 4622324,
    value: "drop-shadow(1px, 1px, 2px)"
  }
];

id String inherited

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

layers Collection<Layer>autocast

Autocasts from Layer[]

A collection of operational layers. This property contains the operational layers, such as FeatureLayers, WebTileLayers and GraphicsLayers that may be queried, assigned different renderers, analyzed, etc. It does not include basemaps.

A layer is a collection of one or more features, or graphics, that represent real-world phenomena. Each feature contains a symbol and geographic data that allows it to be rendered on the map as a graphic with spatial context. Features within the layer may also contain data attributes that provide additional information that may be viewed in popup windows and used for rendering the layer.

Layers may be added in the constructor, with the add() or addMany() methods, or directly to the layers collection using add() or addMany().

In 3D, for layers that are rendered on the terrain, the order of the layers also depends on the type of layer. Tiled layers (VectorTileLayer, WebTileLayer, WMTSLayer) are always drawn first in the same order as specified in the layer collection. Dynamic layers (MapImageLayer, ImageryLayer, WMSLayer, and feature based layers with elevation mode on-the-ground) are rendered on top using the order from the layer collection.

A layer may only be added to one parent. Adding the same layer to multiple Maps or GroupLayers is not possible. If you attempt to do so, the layer will automatically be removed from its current parent and placed in the new parent.

var layer = new GraphicsLayer();
// The layer belongs to map1
map1.layers.add(layer);
// The layer now belongs to map2
// and implicitly does: map1.layers.remove(layer)
map2.layers.add(layer);

To access tables from feature layers, use the tables property in either Map or WebMap classes.

Example:

// Add layers in the constructor of Map using an array
var fl = new FeatureLayer(url);
var gl = new GraphicsLayer();
var map = new Map({
  layers: [fl, gl]
});

// Add layers using add()
map.addMany([fl, gl]);

// Add layers using layers collection
map.layers.addMany([fl, gl]);

// Add layers using layers collection's push method
map.layers.push(fl, gl);

listMode String inherited

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 inherited

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

Default Value:false

loadError Errorreadonly inherited

The Error object returned if an error occurred while loading.

Default Value:null

loadStatus Stringreadonly inherited

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 inherited

A list of warnings which occurred while loading.

opacity Number inherited

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;

portalItem PortalItem

The portal item from which the layer is loaded. If the portal item references a Feature Service or Scene Service, then you can specify a single layer to load with the layerId property.

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.

Examples:

// While this example uses FeatureLayer, this same pattern can be
// used for other layers that may be loaded from portalItem ids.
const lyr = new FeatureLayer({
  portalItem: {  // autocasts as new PortalItem()
    id: "caa9bd9da1f4487cb4989824053bb847"
  }  // the first layer in the service is returned
});

// Set hostname when using an on-premise portal (default is ArcGIS Online)
// esriConfig.portalUrl = "http://myHostName.esri.com/arcgis";

// While this example uses FeatureLayer, this same pattern can be
// used for SceneLayers.
const lyr = new FeatureLayer({
  portalItem: {  // autocasts as new PortalItem()
    id: "8d26f04f31f642b6828b7023b84c2188"
  },
  // loads the third item in the given feature service
  layerId: 2
});

// This snippet loads a table hosted in ArcGIS Online.
const table = new FeatureLayer({
  portalItem: { // autocasts as esri/portal/PortalItem
    id: "123f4410054b43d7a0bacc1533ceb8dc"
  }
});

// Before adding the table to the map, it must first be loaded and confirm it is the right type.
table.load().then(function() {
  if (table.isTable) {
    map.tables.add(table);
  }
});

tables Collection<Layer>autocast

Autocasts from Layer[]

A collection of layer instances that are tables saved in a Map and/or a WebMap. In order for the table(s) to be recognized as such, the FeatureLayer's isTable property must return true. A table can be created via one of the options below:

• Referencing the URL to a table in a feature service.
• Create a feature layer using the Layer.fromArcGISServerUrl method and confirm that it is a table using feature layer's isTable property. This can be either a feature service or feature collection.
• Create a feature layer using the Layer.fromPortalItem method and confirm that it is a table using feature layer's isTable property. This can be either a feature service or feature collection.
• Create an in-memory, non-spatial, client-side feature layer.

Beginning with 4.17, it is possible to persist non-spatial, tables in a feature service to a WebMap, although in-memory (feature collection) tables are not yet supported.

Persisting tables within a GroupLayer is not yet supported. If this is needed, add them to the Map and/or WebMap.

Currently, only feature service feature layers are recognized.

To access spatial layers, use the layers property in either Map or WebMap classes.

See also:

• Sample - Creating a FeatureLayer - Add an array of client-side features

• FeatureLayer.isTable

• Sample - Save a web map

Examples:

// This snippet shows how to add a table to a map's table collection.

// FeatureLayer.isTable = false
const featureLayer = new FeatureLayer({
  url: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/SF311/FeatureServer/0"
});

// FeatureLayer.isTable = true
const table = new FeatureLayer({
  url: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/SF311/FeatureServer/1"
});

// Add featureLayer to the map
map.add(featureLayer);

// In order for the table to be stored within
// the map's table collection, load it and confirm it is the right type.

table.load().then(function() {
  // Add the table to the collection
  map.tables.add(table);
  console.log("Table is added to map's table collection");
});

// This snippet shows how to persist a table to an existing web map

// FeatureLayer.isTable = true
const table = new FeatureLayer({
  url: "https://services.arcgis.com/V6ZHFr6zdgNZuVG0/arcgis/rest/services/Crash_details_table/FeatureServer/0"
});

// Create Webmap instance
const webmap = new WebMap({
  portalItem: {
    id: webmapId
  }
});

// When web map is ready, load the table and add it to the web map
webmap.when(function() {
  table.load().then(function() {
    console.log("Adding table");
    // Add table to the webmap's table collection
    webmap.tables.add(table);
  });
});

// Call updateFrom on webmap and pass in the existing view
webmap.updateFrom(view).then(function() {
  // Call saveAs (or save) on the web map
  webmap.saveAs({
    // autocasts as new PortalItem()
    title: "New WebMap"
  });
});

// This snippet shows how to add an in-memory table to a map

// Create the array of objects containing field info
const fields = [{
  name: "ObjectID",
  alias: "ObjectID",
  type: "oid"
},
{
  name: "tree_type",
  alias: "Tree type",
  type: "string"
},
{
  name: "species",
  alias: "Species",
  type: "string"
}];

// Create the array of graphics holding attribute info
const graphics = [{
  attributes: {
    "tree_type": "deciduous",
    "species": "maple",
    "ObjectID": 2
  }
}, {
  attributes: {
    "tree_type": "coniferous",
    "species": "pine",
    "ObjectID": 3
  }
}];

// Create the feature layer (feature collection) table
const table = new FeatureLayer({
  fields: fields,
  objectIdField: "ObjectID",
  source: graphics
});

// Check when map is ready and load the table
map.when(function() {
  table.load().then(function() {
    console.log("Adding table");
    map.tables.add(table);
  });
});

title String

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

When 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

For GroupLayer the type is always "group".

visibilityMode String

Indicates how to manage the visibility of the children layers. Possible values are described in the table below.

Value	Description
independent	Each child layer manages its visibility independent from other layers.
inherited	Each child layer's visibility matches the GroupLayer’s visibility.
exclusive	Only one child layer is visible at a time.

Possible Values:"independent"|"inherited"|"exclusive"

visible Boolean inherited

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

add(layer, index)

Adds a layer to the layers collection. The before-changes, before-add, after-add, after-changes and change events will be emitted when this method is called.

Parameters:

layer Layer|Promise Layer or a promise that resolves to a layer to add to the layers collection.

index Number optional A layer can be added at a specified index in the layers collection. If no index is specified or the index specified is greater than the current number of layers, the layer is automatically appended to the list of layers in the layers collection and the index is normalized.

See also:

• layer collection's push() method

Example:

// add() and push methods can be used
// to add a layer to layers collection

// add a layer to layers collection using add
map.add(layer);

// add a layer at the end of layers collection
map.layers.push(layer);

addMany(layers, index)

Adds a layer or an array of layers to the layers collection. The before-changes, before-add, after-add, after-changes and change events will be emitted when this method is called.

The push() method on the layers collection also can be used to add a layer or layers.

Parameters:

layers Layer[] Layer(s) to be added to the layers collection.

index Number optional A layer can be added at a specified index in the layers collection. If no index is specified or the index specified is greater than the current number of layers, the layer is automatically appended to the list of layers in the layers collection and the index is normalized.

See also:

• layer collection's push() method

Example:

// addMany and push methods can be used
// to add layers to layers collection

// add an array of layers to layers collection using addMany
map.addMany([layer, layer2]);

// add layers to layers collection using push method
map.layers.push(layer, layer2);

cancelLoad()inherited

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

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

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()inherited

Since: ArcGIS API 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}inherited

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:

Type	Description
Boolean	true if a listener was notified

findLayerById(layerId){Layer}

Returns a layer based on the given layer ID.

Parameter:

layerId String The ID assigned to the layer.

Returns:

Type	Description
Layer	Returns the requested layer object.

findTableById(tableId){SearchTable}

Since: ArcGIS API for JavaScript 4.18

Returns a table based on the given table ID.

Parameter:

tableId String The ID assigned to the table.

Returns:

Type	Description
SearchTable	Returns the requested table object.

hasEventListener(type){Boolean}inherited

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.

isFulfilled(){Boolean}inherited

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}inherited

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}inherited

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}inherited

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

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

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

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

Parameter:

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

Returns:

Type	Description
Promise	Resolves when the resources have loaded.

loadAll(){Promise<GroupLayer>}

Since: ArcGIS API for JavaScript 4.9

Loads all the externally loadable resources associated with the group layer. For the group layer this will load all the layers.

Returns:

Type	Description
Promise<GroupLayer>	Resolves when all the loadable resources have been loaded. Rejects if at least one of the loadable resources failed to load.

See also:

• load

Example:

// Load all resources but ignore if one or more of them failed to load
groupLayer.loadAll()
  .catch(function(error) {
    // Ignore any failed resources
  })
  .then(function() {
    console.log("All loaded");
  });

on(type, listener){Object}inherited

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

Parameters:

type String|String[] A event type, or an array of event types, to listen for.

listener Function The function to call when the event is fired.

Returns:

Type	Description
Object	Returns an event handler with a remove() method that can 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);
});

remove(layer){Layer}

Removes the specified layer from the layers collection. The before-changes, before-remove, after-remove, after-changes and change events will be emitted when this method is called.

Parameter:

layer Layer Layer to remove from the layers collection.

Returns:

Type	Description
Layer	Returns the layer removed from the layers collection.

removeAll(){Layer[]}

Removes all layers. The before-changes, before-remove, after-remove, after-changes and change events will be emitted when this method is called.

Returns:

Type	Description
Layer[]	Returns the layers removed from the layers collection.

removeMany(layers){Layer[]}

Removes the specified layers. The before-changes, before-remove, after-remove, after-changes and change events will be emitted when this method is called.

Parameter:

layers Layer[] Array of layers to remove from the layers collection.

Returns:

Type	Description
Layer[]	Returns the layers removed from the layers collection.

reorder(layer, index){Layer}

Changes the layer order. The first layer added is always the base layer, even if its order is changed. The change event will be emitted when this method is called.

In 3D, for layers that are rendered on the terrain, the order of the layers also depends on the type of layer. Tiled layers (VectorTileLayer, WebTileLayer, WMTSLayer) are always drawn first in the same order as specified in the layer collection. Dynamic layers (MapImageLayer, ImageryLayer, WMSLayer, and feature based layers with elevation mode on-the-ground) are rendered on top using the order from the layer collection.

Parameters:

layer Layer The layer to be moved.

index Number The index location for placing the layer. The bottom-most layer has an index of 0.

Returns:

Type	Description
Layer	Returns the layer that was moved.

when(callback, errback){Promise}inherited

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:

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
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

{view: View,layerView: LayerView}

{view: View,error: Error}

{view: View,layerView: LayerView}

Event Details

layerview-createinherited

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-errorinherited

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-destroyinherited

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.