require(["esri/layers/GroupLayer"], function(GroupLayer) { /* code goes here */ });
Class: esri/layers/GroupLayer
Inheritance: GroupLayer Layer Accessor
Since: ArcGIS API for JavaScript 4.0

GroupLayer provides the ability to organize several sublayers into one common layer. Suppose there are several FeatureLayers that all represent water features in different dimensions. For example, wells (points), streams (lines), and lakes (polygons). The GroupLayer provides the functionality to treat them as one layer called "Water Features" even though they are stored as separate feature layers. To accomplish this, create a new GroupLayer and use the add() method to add each of the water layers to the GroupLayer.

The visibility of each layer is managed in the listMode and visibilityMode properties.

An instance of this class is also a Promise. This allows you to execute code once the promise resolves, or when the layer finishes loading its resources. See then() for additional details.

See also:

Constructors

new GroupLayer(properties)

Parameter:
properties Object
optional

See the properties for a list of all the properties that may be passed into the constructor.

Property Overview

Any properties can be set, retrieved or listened to. See the Working with Properties topic.
NameTypeSummaryClass
String

The name of the class.

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more detailsAccessor
String

The unique ID assigned to the layer.

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more detailsLayer
Collection<Layer>

A collection of operational layers.

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more detailsGroupLayer
String

Indicates how the layer should display in the LayerList widget.

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more detailsLayer
Boolean

Indicates whether the layer's resources have loaded.

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more detailsLayer
Error

The Error object returned if an error occurred while loading.

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more detailsLayer
String

Represents the status of a load operation.

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more detailsLayer
Object[]

A list of warnings which occurred while loading.

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more detailsLayer
Number

The opacity of the layer.

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more detailsLayer
PortalItem

The portal item from which the layer is loaded.

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more detailsGroupLayer
String

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

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more detailsGroupLayer
String

For GroupLayer the type is group.

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more detailsGroupLayer
String

Indicates how to manage the visibility of the children layers.

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more detailsGroupLayer
Boolean

Indicates if the layer is visible in the View.

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more detailsLayer

Property Details

declaredClassStringreadonly inherited

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

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

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]);

Indicates how the layer should display in the LayerList widget. The known values are listed below.

ValueDescription
showThe layer is visible in the table of contents.
hideThe layer is hidden in the table of contents.
hide-childrenIf the layer is a GroupLayer, hide the children layers from the table of contents.
Default Value: show

loadedBooleanreadonly inherited

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

Default Value: false

loadErrorErrorreadonly inherited

The Error object returned if an error occurred while loading.

Default Value: null

loadStatusStringreadonly inherited

Represents the status of a load operation.

ValueDescription
not-loadedThe object's resources have not loaded.
loadingThe object's resources are currently loading.
loadedThe object's resources have loaded without errors.
failedThe object's resources failed to load. See loadError for more details.
Default Value: not-loaded

loadWarningsObject[]readonly inherited

A list of warnings which occurred while loading.

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 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.

ValueDescription
independentEach child layer manages its visibility independent from other layers.
inheritedEach child layer's visibility matches the GroupLayer’s visibility.
exclusiveOnly one child layer is visible at a time.

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

NameReturn TypeSummaryClass

Adds a layer to the layers collection.

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more detailsGroupLayer

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

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more detailsGroupLayer
Promise

An instance of this class is a Promise.

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more detailsLayer

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

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more detailsLayer

Emits an event on the instance.

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more detailsLayer
Layer

Returns a layer based on the given layer id.

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more detailsGroupLayer
Boolean

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

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more detailsLayer
Boolean

An instance of this class is a Promise.

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more detailsLayer
Boolean

An instance of this class is a Promise.

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more detailsLayer
Boolean

An instance of this class is a Promise.

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more detailsLayer
Promise

Loads the resources referenced by this class.

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more detailsLayer
Object

Registers an event handler on the instance.

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more detailsLayer
Promise

An instance of this class is a Promise.

more details
more detailsLayer
Layer

Removes the specified layer from the layers collection.

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more detailsGroupLayer
Layer[]

Removes all layers.

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more detailsGroupLayer
Layer[]

Removes the specified layers.

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more detailsGroupLayer
Layer

Changes the layer order.

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more detailsGroupLayer
Promise

An instance of this class is a Promise.

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more detailsLayer

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:
TypeDescription
PromiseReturns 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.

emit(type, event)protectedinherited

Since: ArcGIS API for JavaScript 4.5

Emits an event on the instance. This method should only be used when creating subclasses that inherit from Evented.

Parameters:
type String

The name of the event.

event Object

The event payload.

findLayerById(layerId){Layer}

Returns a layer based on the given layer id.

Parameter:
layerId String

The ID assigned to the layer.

Returns:
TypeDescription
LayerReturns 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:
TypeDescription
BooleanReturns 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:
TypeDescription
BooleanIndicates 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:
TypeDescription
BooleanIndicates 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:
TypeDescription
BooleanIndicates whether the promise has been resolved.

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:
TypeDescription
PromiseResolves 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:
TypeDescription
ObjectReturns an event handler with a remove() method that can be called to stop listening for the event.
PropertyTypeDescription
removeFunctionWhen called, removes the listener from the event.
See also:
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:
TypeDescription
PromiseReturns 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:
TypeDescription
LayerReturns the layer removed from the layers collection.

removeAll(){Layer[]}

Removes all layers.

Returns:
TypeDescription
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:
TypeDescription
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:
TypeDescription
LayerReturns 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:
TypeDescription
PromiseReturns 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

NameTypeSummaryClass
{view: View,layerView: LayerView}

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

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more detailsLayer
{view: View,layerView: LayerView}

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

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more detailsLayer

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-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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