LegendViewModel | API Reference | ArcGIS Maps SDK for JavaScript

Provides the logic for the Legend widget and component, which displays a label and symbol for interpreting the Renderer of each layer in a map. This class may be used to create custom, interactive Legends.

See also

Legend widget - Deprecated since 4.34. Use the Legend component instead.
Legend component
Programming patterns: Widget viewModel pattern

Example

const legend = new Legend({
  view: view,
  viewModel: new LegendViewModel({
    view: view
  })
});
view.ui.add(legend, "bottom-left");

Constructors

LegendViewModel Constructor new LegendViewModel(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 Watch for changes topic.

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Type	Summary	Class
Collection<ActiveLayerInfo>	Collection of ActiveLayerInfo objects used by the legend view to display data in the legend.	LegendViewModel
Boolean	Indicates whether to show the Basemap layers in the Legend.	LegendViewModel
String	The name of the class.	Accessor
Boolean	When `true`, layers will only be shown in the legend if they are visible in the view's extent.	LegendViewModel
LayerInfo []	Defines which layers and sublayers are shown in the legend, including any basemap layers you want visible.	LegendViewModel
Boolean	Indicates whether the viewModel is currently loading.	LegendViewModel
Boolean	If a layer uses a unique value render, only features that satisfy the layer's definition expression will be displayed in the legend when set to true.	LegendViewModel
Boolean	Determines whether to respect the properties of the layers in the map that control the legend's visibility (`minScale`, `maxScale`, `legendEnabled`).	LegendViewModel
String	The view model's state.	LegendViewModel
MapView\|SceneView\|null\|undefined	The view from which the widget will operate.	LegendViewModel

Property Details

activeLayerInfos Property activeLayerInfos Collection<ActiveLayerInfo>autocast Autocasts from Object []

Collection of ActiveLayerInfo objects used by the legend view to display data in the legend. Use this property to hide or display the layer's symbols in the legend when an ActiveLayerInfo is removed from or added to this collection.

basemapLegendVisible Property basemapLegendVisible Boolean

Indicates whether to show the Basemap layers in the Legend.

Default Value:false

Example

legend.viewModel.basemapLegendVisible = true;

declaredClass Inherited Property declaredClass Stringreadonly Inherited from Accessor

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

hideLayersNotInCurrentView Property hideLayersNotInCurrentView Boolean Since: ArcGIS Maps SDK for JavaScript 4.21 LegendViewModel since 4.11, hideLayersNotInCurrentView added at 4.21.

When true, layers will only be shown in the legend if they are visible in the view's extent. When data from a layer is not visible in the view, the layer's legend information will be hidden.

To hide layers completely from the legend, you should set the legendEnabled property of the layer to false.

Default Value:false

See also

respectLayerVisibility

Example

// layers not displayed in the view
// will not be shown in the legend
legend.viewModel.hideLayersNotInCurrentView = true;

layerInfos Property layerInfos LayerInfo[]

Defines which layers and sublayers are shown in the legend, including any basemap layers you want visible. If not set, all layers in the map are displayed in the legend by default, including basemap layers when basemapLegendVisible is true.

loading Property loading Booleanreadonly Since: ArcGIS Maps SDK for JavaScript 4.34 LegendViewModel since 4.11, loading added at 4.34.

Indicates whether the viewModel is currently loading.

Default Value:false

respectLayerDefinitionExpression Property respectLayerDefinitionExpression Boolean Since: ArcGIS Maps SDK for JavaScript 4.34 LegendViewModel since 4.11, respectLayerDefinitionExpression added at 4.34.

If a layer uses a unique value render, only features that satisfy the layer's definition expression will be displayed in the legend when set to true.

Default Value:false

See also

definitionExpression

respectLayerVisibility Property respectLayerVisibility Boolean Since: ArcGIS Maps SDK for JavaScript 4.13 LegendViewModel since 4.11, respectLayerVisibility added at 4.13.

Determines whether to respect the properties of the layers in the map that control the legend's visibility (minScale, maxScale, legendEnabled). By default, a layer's legend elements will not render in the legend given the following conditions:

The layer's legendEnabled property is set to false.
If the view's scale is outside the visibility range defined by the layer's minScale and maxScale properties.

When the respectLayerVisibility property of the legend is set to false, the legend elements for each layer in the map will always display, thus disregarding the minScale, maxScale, and legendEnabled properties for each layer in the map.

Default Value:true

See also

hideLayersNotInCurrentView

Example

// Always displays legend elements for the map's layers
// regardless of their minScale, maxScale, and legendEnabled properties
legend.respectLayerVisibility = false;

state Property state Stringreadonly

The view model's state.

Possible Values:"ready" |"disabled"

Default Value:"disabled"

view Property view MapView |SceneView |null |undefined

The view from which the widget will operate.

Method Overview

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Return Type	Summary	Class
	Adds one or more handles which are to be tied to the lifecycle of the object.	Accessor
Boolean	Returns true if a named group of handles exist.	Accessor
	Removes a group of handles owned by the object.	Accessor

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.

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");
}

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");

Type Definitions

LayerInfo Type Definition LayerInfo

An object that defines a layer, optional sublayer IDs, and a custom title for legend display. Use this to specify which layers and sublayers appear in the legend and how they are labeled with layerInfos.

Properties: layer Layer|Sublayer

A layer to display in the legend.

sublayerIds Number []

optional
The IDs of the sublayers for which to display legend information. Only applicable if the layer is a MapImageLayer, SubtypeGroupLayer or WMSLayer.

title String

optional
Specifies a title for the layer to display above its symbols and descriptions. If no title is specified the service name is used.