LayerListViewModel | API Reference | ArcGIS Maps SDK for JavaScript 4.32

Provides the logic for the LayerList widget. To hide layers in the map from the LayerList widget, set the listMode property on the layer(s) to hide.

See also

Constructors

LayerListViewModel Constructor new LayerListViewModel(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
Boolean	Whether to provide an indication if a layer is being published in the LayerList.	LayerListViewModel
String	The name of the class.	Accessor
ListItemCreatedHandler\|null\|undefined	Specifies a function that accesses each ListItem.	LayerListViewModel
Boolean	Specifies whether to ignore the listMode property of the layers to display all layers.	LayerListViewModel
Collection<ListItem>	A collection of ListItems representing operational layers.	LayerListViewModel
String	The view model's state.	LayerListViewModel
MapView\|SceneView\|null\|undefined	The view from which the widget will operate.	LayerListViewModel

Property Details

checkPublishStatusEnabled Property checkPublishStatusEnabled Boolean Since: ArcGIS Maps SDK for JavaScript 4.25 LayerListViewModel since 4.2, checkPublishStatusEnabled added at 4.25.

Whether to provide an indication if a layer is being published in the LayerList. When a layer is publishing, a rotating square will appear to the right of the list item title. The list item publishing property will be false if checkPublishStatusEnabled is false.

Default Value:false

declaredClass Inherited Property declaredClass Stringreadonly Inherited from Accessor 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.

listItemCreatedFunction Property listItemCreatedFunction ListItemCreatedHandler |null |undefined Since: ArcGIS Maps SDK for JavaScript 4.4 LayerListViewModel since 4.2, listItemCreatedFunction added at 4.4.

Specifies a function that accesses each ListItem. Each list item can be modified according to its modifiable properties. Actions can be added to list items using the actionsSections property of the ListItem.

Default Value:null

Example

layerListViewModel.listItemCreatedFunction = function (event) {

   // The event object contains properties of the
   // layer in the LayerList widget.
   const { item } = event;

   if (item.title === "US Demographics") {
     // open the list item in the LayerList
     item.open = true;
     // change the title to something more descriptive
     item.title = "Population by county";
     // set an action for zooming to the full extent of the layer
     item.actionsSections = [[{
       title: "Go to full extent",
       className: "esri-icon-zoom-out-fixed",
       id: "full-extent"
     }]];
   }
});

listModeDisabled Property listModeDisabled Boolean Since: ArcGIS Maps SDK for JavaScript 4.30 LayerListViewModel since 4.2, listModeDisabled added at 4.30.

Specifies whether to ignore the listMode property of the layers to display all layers. A common use case for listModeDisabled is when you want to use the LayerList to manage and configure a layer's listMode value.

Default Value:false

See also

Layer.listMode

operationalItems Property operationalItems Collection<ListItem>readonly

A collection of ListItems representing operational layers. To hide layers from the LayerList widget, set the listMode property on the layer(s) to hide.

See also

Layer.listMode

state Property state Stringreadonly

The view model's state.

Possible Values:"loading" |"ready" |"disabled"

Default Value:"disabled"

view Property view MapView |SceneView |null |undefined

The view from which the widget will operate.

Default Value:null

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	Emits an event on the instance.	LayerListViewModel
Boolean	Indicates whether there is an event listener on the instance that matches the provided event name.	LayerListViewModel
Boolean	Returns true if a named group of handles exist.	Accessor
	Moves a list item from one position to another in the LayerList widget.	LayerListViewModel
Object	Registers an event handler on the instance.	LayerListViewModel
	Removes a group of handles owned by the object.	Accessor
	Triggers the trigger-action event and executes the given action or action toggle.	LayerListViewModel

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.

emit Method emit(type, event){Boolean} Since: ArcGIS Maps SDK for JavaScript 4.5 LayerListViewModel since 4.2, emit added at 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

hasEventListener Method hasEventListener(type){Boolean}

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.

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");
}

moveListItem Method moveListItem(targetItem, fromParentItem, toParentItem, newIndex) Since: ArcGIS Maps SDK for JavaScript 4.16 LayerListViewModel since 4.2, moveListItem added at 4.16.

Moves a list item from one position to another in the LayerList widget. This allows the user to reorder the operational layers in a map or even reorganize sublayers of GroupLayers. You cannot move MapImageLayer sublayers outside of a MapImageLayer.

For the purposes of the documentation below, an item (or list item) refers to a layer in a map. A parent item refers to a GroupLayer or MapImageLayer, and a child item refers to a sublayer of a GroupLayer or MapImageLayer.

Parameters

targetItem ListItem|null|undefined

The list item (or layer) to move.

fromParentItem ListItem|null|undefined

If the targetItem is a child of a parent list item and you want to move it out of the parentItem, then use this parameter to indicate the parent item to move from.

toParentItem ListItem|null|undefined

The parent list item to move the targetItem to if moving it as a child to another parent item.

newIndex Number

The new index to move the targetItem to. If moving the item as a child to a parent item, then specify the index of the item within that parent.

Examples

// Moves the first layer to the final position in the map
const viewModel = layerList.viewModel;
const item = layerList.operationalItems.at(0);
const lastIndex = layerList.operationalItems.length - 1;

viewModel.moveListItem(item, null, null, lastIndex);

// Moves the first sublayer in the first group layer
// to the first position in the second group layer
const viewModel = layerList.viewModel;
const parentItem1 = layerList.operationalItems.at(0);
const subItem1 = parentItem1.children.at(0);
const parentItem2 = layerList.operationalItems.at(1);

viewModel.moveListItem(subItem1, parentItem1, parentItem2, 0);

on Method on(type, listener){Object}

Registers an event handler on the instance. Call this method to hook an event with a listener.

Parameters

type String|String []

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);
});

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");

triggerAction Method triggerAction(action, item)

Triggers the trigger-action event and executes the given action or action toggle.

Parameters

action ActionButton|ActionToggle

The action to execute.

item ListItem

An item associated with the action.

Event Overview

Name	Type	Summary	Class
	{action: ActionButton\|ActionToggle,item: ListItem}	Fires after the user clicks on an action or action toggle inside the LayerList widget.	LayerListViewModel

Event Details

trigger-action Event trigger-action

Fires after the user clicks on an action or action toggle inside the LayerList widget. This event may be used to define a custom function to execute when particular actions are clicked.

Properties: action ActionButton|ActionToggle

The action clicked by the user.

item ListItem

An item associated with the action.