ESM: import UnknownLayer from "@arcgis/core/layers/UnknownLayer.js";
CDN: const UnknownLayer = await $arcgis.import("@arcgis/core/layers/UnknownLayer.js");
Class: @arcgis/core/layers/UnknownLayer
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.
Property Overview Any properties can be set, retrieved or listened to. See the Watch for changes topic.Show inherited properties Hide inherited properties
Property DetailsInherited
Property declaredClass Stringreadonly
Since: ArcGIS Maps SDK for JavaScript 4.7 Accessor since 4.0, declaredClass added at 4.7.
The name of the class. The declared class name is formatted as esri.folder.className
.
The full extent of the layer. By default, this is worldwide. This property may be used to set the extent of the view to match a layer's extent so that its features appear to fill the view. See the sample snippet below.
Example
// Once the layer loads, set the view's extent to the layer's fullextent
layer.when(function(){
view.extent = layer.fullExtent;
});
Inherited
Property id String
The unique ID assigned to the layer. If not set by the developer, it is automatically generated when the layer is loaded.
Inherited
Property listMode String
Indicates how the layer should display in the LayerList widget. The possible values are listed below.
Possible Values:"show" |"hide" |"hide-children"
The Error object returned if an error occurred while loading.
Inherited
Property loadStatus Stringreadonly
Represents the status of a load operation.
Value Description not-loaded The object's resources have not loaded. loading The object's resources are currently loading. loaded The object's resources have loaded without errors. failed The object's resources failed to load. See loadError for more details.Possible Values:"not-loaded" |"loading" |"failed" |"loaded"
Default Value:"not-loaded"
Inherited
Property loadWarnings Object[]readonly
A list of warnings which occurred while loading.
Inherited
Property loaded Booleanreadonly
Indicates whether the layer's resources have loaded. When true
, all the properties of the object can be accessed.
Inherited
Property opacity Number
The opacity of the layer. This value can range between 1
and 0
, where 0
is 100 percent transparent and 1
is completely opaque.
Example
// Makes the layer 50% transparent
layer.opacity = 0.5;
Since: ArcGIS Maps SDK for JavaScript 4.27 Layer since 4.0, parent added at 4.27.
The parent to which the layer belongs.
Inherited
Property persistenceEnabled Booleanreadonly
Since: ArcGIS Maps SDK for JavaScript 4.28 Layer since 4.0, persistenceEnabled added at 4.28.
When true
, the layer can be persisted. This property only has an effect for layers that are part of the WebMap or WebScene spec.
The title of the layer used to identify it in places such as the LayerList widget.
If the layer is loaded from a portal item, the title of the portal item will be used. If a layer is loaded as part of a webmap or a webscene, then the title of the layer as stored in the webmap/webscene will be used.
Inherited
Property uid Stringreadonly
Since: ArcGIS Maps SDK for JavaScript 4.33 Layer since 4.0, uid added at 4.33.
An automatically generated unique identifier assigned to the instance. The unique id is generated each time the application is loaded.
Since: ArcGIS Maps SDK for JavaScript 4.30 Layer since 4.0, visibilityTimeExtent added at 4.30.
Specifies a fixed time extent during which a layer should be visible. This property can be used to configure a layer that does not have time values stored in an attribute field to work with time. Once configured, the TimeSlider widget will display the layer within the set time extent. In the case that only one of the start or end date values are available, the layer remains visible indefinitely in the direction where there is no time value.
Aerial imagery can capture seasonal variations in vegetation, water bodies, and land use patterns. For example, in agricultural regions, aerial imageries taken during different growing seasons provide insights into crop health and productivity. Defining a fixed time extent on imageries from specific time periods provides temporal context and facilitates focused analysis based on specific time periods or events.
Inherited
Property 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.
Example
// The layer is no longer visible in the view
layer.visible = false;
// Watch for changes in the layer's visibility
// and set the visibility of another layer when it changes
reactiveUtils.watch(
() => layer.visible,
(visible) => {
if (visible) {
anotherLayer.visible = true;
} else {
anotherLayer.visible = false;
}
}
);
Show inherited methods Hide inherited methods
Method DetailsInherited
Method addHandles(handleOrHandles, groupKey)
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, addHandles added at 4.25.
Adds one or more handles which are to be tied to the lifecycle of the object. The handles will be removed when the object is destroyed.
// Manually manage handles
const handle = reactiveUtils.when(
() => !view.updating,
() => {
wkidSelect.disabled = false;
},
{ once: true }
);
this.addHandles(handle);
// Destroy the object
this.destroy();
Parameters
Handles marked for removal once the object is destroyed.
groupKey *
optionalKey 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.
Inherited
Method cancelLoad()
Cancels a load() operation if it is already in progress.
Inherited
Method createLayerView(view, options){Promise<LayerView>}
Called by the views, such as MapView and SceneView, when the layer is added to the Map.layers collection and a layer view must be created for it. This method is used internally and there is no use case for invoking it directly.
Parameters
view *
The parent view.
optionalAn object specifying additional options. See the object specification table below for the required properties of this object.
Returns
Inherited
Method destroy()
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.
Inherited
Method emit(type, event){Boolean}
Since: ArcGIS Maps SDK for JavaScript 4.5 Layer since 4.0, emit added at 4.5.
Emits an event on the instance. This method should only be used when creating subclasses of this class.
Parameters
The name of the event.
optionalThe event payload.
Returns
Type Description Booleantrue
if a listener was notified
Inherited
Method fetchAttributionData(){Promise<Object>}
Fetches custom attribution data for the layer when it becomes available.
Returns
Type Description Promise<Object> Resolves to an object containing custom attribution data for the layer.Inherited
Method hasEventListener(type){Boolean}
Indicates whether there is an event listener on the instance that matches the provided event name.
Returns
Type Description Boolean Returns true if the class supports the input event.Inherited
Method hasHandles(groupKey){Boolean}
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, hasHandles added at 4.25.
Returns true if a named group of handles exist.
Parameter
groupKey *
optionalA group key.
Returns
Type Description Boolean Returnstrue
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");
}
Inherited
Method isFulfilled(){Boolean}
isFulfilled()
may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected). If it is fulfilled, true
will be returned.
Returns
Type Description Boolean Indicates whether creating an instance of the class has been fulfilled (either resolved or rejected).Inherited
Method isRejected(){Boolean}
isRejected()
may be used to verify if creating an instance of the class is rejected. If it is rejected, true
will be returned.
Returns
Type Description Boolean Indicates whether creating an instance of the class has been rejected.Inherited
Method isResolved(){Boolean}
isResolved()
may be used to verify if creating an instance of the class is resolved. If it is resolved, true
will be returned.
Returns
Type Description Boolean Indicates whether creating an instance of the class has been resolved.Inherited
Method load(options){Promise}
Loads the resources referenced by this class. This method automatically executes for a View and all of the resources it references in Map if the view is constructed with a map instance.
This method must be called by the developer when accessing a resource that will not be loaded in a View.
The load()
method only triggers the loading of the resource the first time it is called. The subsequent calls return the same promise.
It's possible to provide a signal
to stop being interested into a Loadable
instance load status. When the signal is aborted, the instance does not stop its loading process, only cancelLoad can abort it.
Parameters
optionalAdditional options.
Specification
optionalSignal 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.Inherited
Method on(type, listener){Object}
Registers an event handler on the instance. Call this method to hook an event with a listener.
Returns
Type Description Object Returns an event handler with aremove()
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);
});
Inherited
Method removeHandles(groupKey)
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, removeHandles added at 4.25.
Removes a group of handles owned by the object.
Parameter
groupKey *
optionalA 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");
Inherited
Method when(callback, errback){Promise}
Since: ArcGIS Maps SDK for JavaScript 4.6 Layer since 4.0, when added at 4.6.
when()
may be leveraged once an instance of the class is created. This method takes two input parameters: a callback
function and an errback
function. The callback
executes when the instance of the class loads. The errback
executes if the instance of the class fails to load.
Parameters
optionalThe function to call when the promise resolves.
optionalThe function to execute when the promise fails.
Returns
Type Description Promise Returns a new promise for the result ofcallback
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
});
Show inherited events Hide inherited events
Event DetailsInherited
Event layerview-create
Fires after the layer's LayerView is created and rendered in a view.
The view in which the layerView
was created.
The LayerView rendered in the view representing the layer in layer
.
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;
});
Inherited
Event layerview-create-error
Fires when an error emits during the creation of a LayerView after a layer has been added to the map.
The view that failed to create a layerview for the layer emitting this event.
An error object describing why the layer view failed to create.
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);
});
Inherited
Event layerview-destroy
Fires after the layer's LayerView is destroyed and no longer renders in a view.
The view in which the layerView
was destroyed.
The destroyed LayerView representing the layer.
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