UnknownLayer

AMD: require(["esri/layers/UnknownLayer"], (UnknownLayer) => { /* code goes here */ });
ESM: import UnknownLayer from "@arcgis/core/layers/UnknownLayer";
Class: esri/layers/UnknownLayer
Inheritance: UnknownLayer Layer Accessor
Since: ArcGIS API 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 Working with Properties topic.
Show inherited properties Hide inherited properties
Name Type Summary Class
Stringmore details

The name of the class.

more detailsAccessor
Extentmore details

The full extent of the layer.

more detailsLayer
Stringmore details

The unique ID assigned to the layer.

more detailsLayer
Stringmore details

Indicates how the layer should display in the LayerList widget.

more detailsLayer
Booleanmore details

Indicates whether the layer's resources have loaded.

more detailsLayer
Errormore details

The Error object returned if an error occurred while loading.

more detailsLayer
Stringmore details

Represents the status of a load operation.

more detailsLayer
Object[]more details

A list of warnings which occurred while loading.

more detailsLayer
Numbermore details

The opacity of the layer.

more detailsLayer
Stringmore details

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

more detailsLayer
Stringmore details For UnknownLayer the type is always "unknown". more detailsUnknownLayer
Booleanmore details

Indicates if the layer is visible in the View.

more detailsLayer

Property Details

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.

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 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;

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.

If the layer is loaded from a portal item, the title of the portal item will be used. If a layer is loaded as part of a webmap or a webscene, then the title of the layer as stored in the webmap/webscene will be used.

type Stringreadonly

For UnknownLayer the type is always "unknown".

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

Show inherited methods Hide inherited methods
Name Return Type Summary Class
more details

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

more detailsLayer
Promise<LayerView>more details

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.

more detailsLayer
more details

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

more detailsLayer
Booleanmore details

Emits an event on the instance.

more detailsLayer
Promise<Object>more details

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

more detailsLayer
Booleanmore details

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

more detailsLayer
Booleanmore details

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

more detailsLayer
Booleanmore details

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

more detailsLayer
Booleanmore details

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

more detailsLayer
Promisemore details

Loads the resources referenced by this class.

more detailsLayer
Objectmore details

Registers an event handler on the instance.

more detailsLayer
Promisemore details

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

more detailsLayer

Method Details

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:
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:
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
fetchAttributionData(){Promise<Object>}inherited

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(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.
on(type, listener){Object}inherited

Registers an event handler on the instance. Call this method to hook an event with a listener. See the Events summary table for a list of supported events.

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);
});
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
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}
more details

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

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

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

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

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

more details Layer

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:
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:
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.

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