LayerListViewModel

AMD: require(["esri/widgets/LayerList/LayerListViewModel"], (LayerListVM) => { /* code goes here */ });
ESM: import LayerListVM from "@arcgis/core/widgets/LayerList/LayerListViewModel";
Class: esri/widgets/LayerList/LayerListViewModel
Inheritance: LayerListViewModel Accessor
Since: ArcGIS API for JavaScript 4.2

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

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 Working with Properties topic.
Show inherited properties Hide inherited properties
Name Type Summary Class
Boolean

Whether to provide an indication if a layer is being published in the LayerList.

more details
LayerListViewModel
String

The name of the class.

more details
Accessor
ListItemCreatedHandler

Specifies a function that accesses each ListItem.

more details
LayerListViewModel
Collection<ListItem>

A collection of ListItems representing operational layers.

more details
LayerListViewModel
String

The view model's state.

more details
LayerListViewModel
MapView|SceneView

The view from which the widget will operate.

more details
LayerListViewModel

Property Details

checkPublishStatusEnabled Boolean
Since: ArcGIS API for JavaScript 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 Stringreadonly inherited
Since: ArcGIS API for JavaScript 4.7

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

listItemCreatedFunction ListItemCreatedHandler
Since: ArcGIS API for JavaScript 4.4

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

Example
layerListViewModel.listItemCreatedFunction = function (event) {

   // The event object contains properties of the
   // layer in the LayerList widget.

   let item = event.item;

   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"
     }]];
   }
});
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
state Stringreadonly

The view model's state.

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

Default Value:disabled

The view from which the widget will operate.

Method Overview

Show inherited methods Hide inherited methods
Name Return Type Summary Class

Adds one or more handles which are to be tied to the lifecycle of the object.

more details
Accessor
Boolean

Returns true if a named group of handles exist.

more details
Accessor

Moves a list item from one position to another in the LayerList widget.

more details
LayerListViewModel

Removes a group of handles owned by the object.

more details
Accessor

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

more details
LayerListViewModel

Method Details

addHandles(handleOrHandles, groupKey)inherited
Since: ArcGIS API for JavaScript 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 }
);

// Handle gets removed when the object is destroyed.
this.addHandles(handle);
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(groupKey){Boolean}inherited
Since: ArcGIS API for JavaScript 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(targetItem, fromParentItem, toParentItem, newIndex)
Since: ArcGIS API for JavaScript 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 a GroupLayer as a sublayer to another GroupLayer. You also 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

The list item (or layer) to move.

fromParentItem ListItem

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

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.getItemAt(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.getItemAt(0);
const subItem1 = parentItem1.children.getItemAt(0);
const parentItem2 = layerList.operationalItems.getItemAt(1);

viewModel.moveListItem(subItem1, parentItem1, parentItem2, 0);
removeHandles(groupKey)inherited
Since: ArcGIS API for JavaScript 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(action, item)

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

Parameters

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.

more details
LayerListViewModel

Event Details

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

The action clicked by the user.

item ListItem

An item associated with the action.

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