UnknownLayer

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

Represents a layer whose type could not be determined. For example, when loading a layer from a URL and the layer type cannot be determined, then it is represented as an instance of this class.

An instance of this class may also be used when loading a WebMap or a WebScene. If the service of one of the layers in the WebMap/WebScene is not available and the layer type cannot be determined, then it is represented as an UnknownLayer. It is important to note that constructing layers from this class is not supported.

See also

Property Overview

Any properties can be set, retrieved or listened to. See the Watch for changes topic.
Show inherited properties Hide inherited properties
Name Type Summary Class

The name of the class.

Accessor

The full extent of the layer.

Layer

The unique ID assigned to the layer.

Layer

Indicates how the layer should display in the LayerList widget.

Layer

The Error object returned if an error occurred while loading.

Layer

Represents the status of a load operation.

Layer

A list of warnings which occurred while loading.

Layer

Indicates whether the layer's resources have loaded.

Layer

The opacity of the layer.

Layer

The parent to which the layer belongs.

Layer

When true, the layer can be persisted.

Layer

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

Layer
For UnknownLayer the type is always "unknown". UnknownLayer

Specifies a fixed time extent during which a layer should be visible.

Layer

Indicates if the layer is visible in the View.

Layer

Property Details

declaredClass

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

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

fullExtent

Inherited
Property
fullExtent Extent |null |undefinedautocast
Inherited from Layer

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

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

id

Inherited
Property
id String
Inherited from Layer

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

listMode

Inherited
Property
listMode String
Inherited from Layer

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"

loadError

Inherited
Property
loadError Errorreadonly
Inherited from Layer

The Error object returned if an error occurred while loading.

Default Value:null

loadStatus

Inherited
Property
loadStatus Stringreadonly
Inherited from Layer

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

Inherited
Property
loadWarnings Object[]readonly
Inherited from Layer

A list of warnings which occurred while loading.

loaded

Inherited
Property
loaded Booleanreadonly
Inherited from Layer

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

Default Value:false

opacity

Inherited
Property
opacity Number
Inherited from Layer

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

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

parent

Inherited
Property
parent Map |Basemap |Ground |GroupLayer |CatalogDynamicGroupLayer |CatalogLayer
Inherited from Layer
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

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

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

Default Value:false

title

Inherited
Property
title String |null |undefined
Inherited from Layer

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

For UnknownLayer the type is always "unknown".

visibilityTimeExtent

Inherited
Property
visibilityTimeExtent TimeExtent |null |undefinedautocast
Inherited from Layer
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.

visible

Inherited
Property
visible Boolean
Inherited from Layer

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;

// 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;
    }
  }
);

Method Overview

Show inherited methods Hide inherited methods
Name Return Type Summary Class

Adds one or more handles which are to be tied to the lifecycle of the object.

Accessor

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

Layer
Promise<LayerView>

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

Layer

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

Layer

Emits an event on the instance.

Layer
Promise<Object>

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

Layer

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

Layer

Returns true if a named group of handles exist.

Accessor

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

Layer

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

Layer

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

Layer
Promise

Loads the resources referenced by this class.

Layer

Registers an event handler on the instance.

Layer

Removes a group of handles owned by the object.

Accessor
Promise

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

Layer

Method Details

addHandles

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

Adds one or more handles which are to be tied to the lifecycle of the object. The handles will be removed when the object is destroyed.

// Manually manage handles
const handle = reactiveUtils.when(
  () => !view.updating,
  () => {
    wkidSelect.disabled = false;
  },
  { once: true }
);

this.addHandles(handle);

// Destroy the object
this.destroy();
Parameters
handleOrHandles WatchHandle|WatchHandle[]

Handles marked for removal once the object is destroyed.

groupKey *
optional

Key identifying the group to which the handles should be added. All the handles in the group can later be removed with Accessor.removeHandles(). If no key is provided the handles are added to a default group.

cancelLoad

Inherited
Method
cancelLoad()
Inherited from Layer

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

createLayerView

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

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

Parameters
view *

The parent view.

options Object
optional

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

Specification
signal AbortSignal
optional

A signal to abort the creation of the layerview.

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

destroy

Inherited
Method
destroy()
Inherited from Layer
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

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

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

Parameters
type String

The name of the event.

event Object
optional

The event payload.

Returns
Type Description
Boolean true if a listener was notified

fetchAttributionData

Inherited
Method
fetchAttributionData(){Promise<Object>}
Inherited from Layer

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.

hasEventListener

Inherited
Method
hasEventListener(type){Boolean}
Inherited from Layer

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

Parameter
type String

The name of the event.

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

hasHandles

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

Returns true if a named group of handles exist.

Parameter
groupKey *
optional

A group key.

Returns
Type Description
Boolean Returns true if a named group of handles exist.
Example
// Remove a named group of handles if they exist.
if (obj.hasHandles("watch-view-updates")) {
  obj.removeHandles("watch-view-updates");
}

isFulfilled

Inherited
Method
isFulfilled(){Boolean}
Inherited from Layer

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

Inherited
Method
isRejected(){Boolean}
Inherited from Layer

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

Inherited
Method
isResolved(){Boolean}
Inherited from Layer

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

Inherited
Method
load(signal){Promise}
Inherited from Layer

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

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

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

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

Parameter
signal AbortSignal
optional

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

Returns
Type Description
Promise Resolves when the resources have loaded.

on

Inherited
Method
on(type, listener){Object}
Inherited from Layer

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

Parameters

An event or an array of events to listen for.

listener Function

The function to call when the event fires.

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

removeHandles

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

Removes a group of handles owned by the object.

Parameter
groupKey *
optional

A group key or an array or collection of group keys to remove.

Example
obj.removeHandles(); // removes handles from default group

obj.removeHandles("handle-group");
obj.removeHandles("other-handle-group");

when

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

when() may be leveraged once an instance of the class is created. This method takes two input parameters: a callback function and an errback function. The callback executes when the instance of the class loads. The errback executes if the instance of the class fails to load.

Parameters
callback Function
optional

The function to call when the promise resolves.

errback Function
optional

The function to execute when the promise fails.

Returns
Type Description
Promise Returns a new promise for the result of callback that may be used to chain additional functions.
Example
// Although this example uses MapView, any class instance that is a promise may use when() in the same way
let view = new MapView();
view.when(function(){
  // This function will execute once the promise is resolved
}, function(error){
  // This function will execute if the promise is rejected due to an error
});

Event Overview

Show inherited events Hide inherited events
Name Type Summary Class
{view: View,layerView: LayerView}

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

Layer
{view: View,error: Error}

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

Layer
{view: View,layerView: LayerView}

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

Layer

Event Details

layerview-create

Inherited
Event
layerview-create
Inherited from Layer

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

Inherited
Event
layerview-create-error
Inherited from Layer

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

Inherited
Event
layerview-destroy
Inherited from Layer

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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