Property Overview

Property Details

declaredClassStringreadonly

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

idString

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

layersCollection autocast

A collection of operational layers. This property only contains interactive 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().

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);

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]);

listModeString

Indicates how the layer should display in the LayerList widget. The known 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, hide the children layers from the table of contents.

Default Value: show

loadedBooleanreadonly

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

Default Value: false

loadErrorErrorreadonly

The Error object returned if an error occurred while loading.

Default Value: null

loadStatusStringreadonly

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.

Default Value: not-loaded

loadWarningsObject[]readonly

A list of warnings which occurred while loading.

opacityNumber

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;

portalItemPortalItem

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 to load with the layerId property.

Examples:

// while this example uses FeatureLayer, this same pattern can be
// used for other layers that may be loaded from portalItem ids
var 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
var lyr = new FeatureLayer({
  portalItem: {  // autocasts as new PortalItem()
    id: "8d26f04f31f642b6828b7023b84c2188"
  },
  // loads the third item in the given feature service
  layerId: 2
});

titleString

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.

typeStringreadonly

For GroupLayer the type is group.

visibilityModeString

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.

visibleBoolean

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(layers, index)

Adds a layer to the layers collection.

Parameters:

layers Layer Layer 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.

addMany(layers, index)

Adds a layer or an array of layers to the layers collection.

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.

always(callbackOrErrback){Promise}inherited

An instance of this class is a Promise. Therefore always() may be used to execute a function if the promise is rejected or resolved. The input function will always execute no matter the response. For more information about promises, see the Working with Promises guide page.

Parameter:

callbackOrErrback Function optional The function to execute when the promise is rejected or resolved.

Returns:

Type	Description
Promise	Returns a new promise for the result of callbackOrErrback.

Example:

// Although this example uses MapView, any class instance that is a promise may use always() in the same way
var view = new MapView();
view.always(function(){
  // This function will always execute whether or not the promise is resolved or rejected
});

cancelLoad()inherited

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

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.

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

An instance of this class is a Promise. Therefore isFulfilled() may be used to verify if the promise is fulfilled (either resolved or rejected). If it is fulfilled, true will be returned. See the Working with Promises guide page for more information about promises.

Returns:

Type	Description
Boolean	Indicates whether the promise has been fulfilled (either resolved or rejected).

isRejected(){Boolean}inherited

An instance of this class is a Promise. Therefore isRejected() may be used to verify if the promise is rejected. If it is rejected, true will be returned. See the Working with Promises guide page for more information about promises.

Returns:

Type	Description
Boolean	Indicates whether the promise has been rejected.

isResolved(){Boolean}inherited

An instance of this class is a Promise. Therefore isResolved() may be used to verify if the promise is resolved. If it is resolved, true will be returned. See the Working with Promises guide page for more information about promises.

Returns:

Type	Description
Boolean	Indicates whether the promise has been resolved.

load(){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.

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 listened events.

Parameters:

type String The name of event 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. Property Type Description remove Function When called, removes the listener from the event.

See also:

• dojo/on

Example:

view.on("click", function(event){
  // event is the event handle returned after the event fires.
  console.log(event.mapPoint);
});

otherwise(errback){Promise}inherited

An instance of this class is a Promise. Use otherwise() to call a function once the promise is rejected.

Parameter:

errback Function optional The function to execute when the promise fails.

Returns:

Type	Description
Promise	Returns a new promise for the result of errback.

Example:

// Although this example uses MapView, any class instance that is a promise may use otherwise() in the same way
var view = new MapView();
view.otherwise(function(error){
  // This function will execute if the promise is rejected due to an error
});

remove(layer){Layer}

Removes the specified layer from the layers collection.

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.

Returns:

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

removeMany(layers){Layer[]}

Removes the specified layers.

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.

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.

then(callback, errback, progback){Promise}inherited

An instance of this class is a Promise. Therefore then() 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 promise resolves (when the instance of the class loads). The errback executes if the promise fails. See the Working with Promises guide page for additional details.

Parameters:

callback Function optional The function to call when the promise resolves.

errback Function optional The function to execute when the promise fails.

progback Function optional The function to invoke when the promise emits a progress update.

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 then() in the same way
var view = new MapView();
view.then(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,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-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.