LayerList

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

The LayerList widget provides a way to display a list of layers, and switch on/off their visibility. The ListItem API provides access to each layer's properties, allows the developer to configure actions related to the layer, and allows the developer to add content to the item related to the layer.

To hide layers in the map from the LayerList widget, you must set the listMode property on the desired layers to hide.

For information about gaining full control of widget styles, see the Styling topic.
See also
Example
let layerList = new LayerList({
  view: view
});
// Adds widget below other elements in the top left corner of the view
view.ui.add(layerList, {
  position: "top-left"
});

Constructors

LayerList

Constructor
new LayerList(properties)
Parameter
properties Object
optional

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

Example
// typical usage
let layerlist = new LayerList({
  view: view
});

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

Indicates whether the widget is collapsed.

LayerList
String|HTMLElement

The ID or node representing the DOM element containing the widget.

Widget
String

The name of the class.

Accessor
Boolean

Indicates whether list items may be reordered within the list by dragging and dropping.

LayerList
String

Placeholder text used in the filter input if visibleElements.filter is true.

LayerList
String

The value of the filter input if visibleElements.filter is true.

LayerList
Number

Indicates the heading level to use for the heading of the widget.

LayerList
String

Icon which represents the widget.

LayerList
String

The widget's default CSS icon class.

LayerList
String

The unique ID assigned to the widget when the widget is created.

Widget
String

The widget's default label.

LayerList
ListItemCreatedHandler

A function that executes each time a ListItem is created.

LayerList
Number

The minimum number of list items required to enable drag and drop reordering with dragEnabled.

LayerList
Number

The minimum number of list items required to display the visibleElements.filter input box.

LayerList
Boolean

Indicates whether more than one list item may be selected by the user at a single time.

LayerList
Collection<ListItem>

A collection of ListItems representing operational layers.

LayerList
Collection<ListItem>

A collection of selected ListItems representing operational layers selected by the user.

LayerList
Boolean

Indicates whether list items may be selected by the user.

LayerList
String

Specifies the selection mode.

LayerList
MapView|SceneView

A reference to the MapView or SceneView.

LayerList
LayerListViewModel

The view model for this widget.

LayerList
String

Determines the icons used to indicate visibility.

LayerList
Boolean

Indicates whether the widget is visible.

Widget
VisibleElements

The visible elements that are displayed within the widget.

LayerList

Property Details

collapsed

Property
collapsed Boolean
Since: ArcGIS Maps SDK for JavaScript 4.29 LayerList since 4.2, collapsed added at 4.29.

Indicates whether the widget is collapsed. When collapsed, only the collapse button and heading are displayed.

Default Value:false
See also
Example
layerList.collapsed = true;

container

Inherited
Property
container String|HTMLElement
Inherited from Widget

The ID or node representing the DOM element containing the widget. This property can only be set once. The following examples are all valid use case when working with widgets.

Examples
// Create the HTML div element programmatically at runtime and set to the widget's container
const basemapGallery = new BasemapGallery({
  view: view,
  container: document.createElement("div")
});

// Add the widget to the top-right corner of the view
view.ui.add(basemapGallery, {
  position: "top-right"
});
// Specify an already-defined HTML div element in the widget's container

const basemapGallery = new BasemapGallery({
  view: view,
  container: basemapGalleryDiv
});

// Add the widget to the top-right corner of the view
view.ui.add(basemapGallery, {
  position: "top-right"
});

// HTML markup
<body>
  <div id="viewDiv"></div>
  <div id="basemapGalleryDiv"></div>
</body>
// Specify the widget while adding to the view's UI
const basemapGallery = new BasemapGallery({
  view: view
});

// Add the widget to the top-right corner of the view
view.ui.add(basemapGallery, {
  position: "top-right"
});

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.

dragEnabled

Property
dragEnabled Boolean
Since: ArcGIS Maps SDK for JavaScript 4.29 LayerList since 4.2, dragEnabled added at 4.29.

Indicates whether list items may be reordered within the list by dragging and dropping. MapImageLayer sublayers can be reordered only within their parent MapImageLayer and can not be dragged out as a separate layer. Drag won't be enabled until the number of list items is equal to or greater than than the value set set in minDragEnabledItems.

Default Value:false
See also
Example
layerList.dragEnabled = true;

filterPlaceholder

Property
filterPlaceholder String
Since: ArcGIS Maps SDK for JavaScript 4.29 LayerList since 4.2, filterPlaceholder added at 4.29.

Placeholder text used in the filter input if visibleElements.filter is true.

Default Value:""
See also
Example
layerList.filterPlaceholder = "Filter layers";

filterText

Property
filterText String
Since: ArcGIS Maps SDK for JavaScript 4.29 LayerList since 4.2, filterText added at 4.29.

The value of the filter input if visibleElements.filter is true.

Default Value:""
See also
Example
reactiveUtils.watch(
  () => layerList.filterText,
  (filterText) => console.log(filterText)
);

headingLevel

Property
headingLevel Number
Since: ArcGIS Maps SDK for JavaScript 4.29 LayerList since 4.2, headingLevel added at 4.29.

Indicates the heading level to use for the heading of the widget. By default, the heading is rendered as a level 2 heading (e.g., <h2>Layer List</h2>). Depending on the widget's placement in your app, you may need to adjust this heading for proper semantics. This is important for meeting accessibility standards.

Default Value:2
See also
Example
layerList.headingLevel = 3;

icon

Property
icon String
Since: ArcGIS Maps SDK for JavaScript 4.27 LayerList since 4.2, icon added at 4.27.

Icon which represents the widget. It is typically used when the widget is controlled by another one (e.g. in the Expand widget).

Default Value:null
See also

iconClass

Property
iconClass String
Since: ArcGIS Maps SDK for JavaScript 4.7 LayerList since 4.2, iconClass added at 4.7.
Deprecated since 4.27. Use icon instead.

The widget's default CSS icon class.

id

Inherited
Property
id String
Inherited from Widget

The unique ID assigned to the widget when the widget is created. If not set by the developer, it will default to the container ID, or if that is not present then it will be automatically generated.

label

Property
label String
Since: ArcGIS Maps SDK for JavaScript 4.7 LayerList since 4.2, label added at 4.7.

The widget's default label.

listItemCreatedFunction

Property
listItemCreatedFunction ListItemCreatedHandler
Since: ArcGIS Maps SDK for JavaScript 4.4 LayerList since 4.2, listItemCreatedFunction added at 4.4.

A function that executes each time a ListItem is created. Use this function to add actions and panels to list items, and to override the default settings of a list item. Actions can be added to list items using the actionsSections property of the ListItem.

Example
let layerList = new LayerList({
  view: view,
  // executes for each ListItem in the LayerList
  listItemCreatedFunction: async function (event) {

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

    let item = event.item;

    // Wait for the layer to load and the item title to become available
    await item.layer.when();

    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"
      }]];
    }
  }
});

minDragEnabledItems

Property
minDragEnabledItems Number
Since: ArcGIS Maps SDK for JavaScript 4.29 LayerList since 4.2, minDragEnabledItems added at 4.29.

The minimum number of list items required to enable drag and drop reordering with dragEnabled.

Default Value:2
See also
Example
layerList.dragEnabled = true;
layerList.minDragEnabledItems = 5;

minFilterItems

Property
minFilterItems Number
Since: ArcGIS Maps SDK for JavaScript 4.29 LayerList since 4.2, minFilterItems added at 4.29.

The minimum number of list items required to display the visibleElements.filter input box.

Default Value:10
See also
Example
layerList.visibleElements.filter = true;
layerList.minFilterItems = 5;

multipleSelectionEnabled

Property
multipleSelectionEnabled Boolean
Deprecated since 4.29. Use selectionMode instead.

Indicates whether more than one list item may be selected by the user at a single time. You must first set selectionEnabled to true for this property to have an effect on the widget.

Selected items are available in the selectedItems property.

Default Value:false
See also
Example
layerList.selectionEnabled = true;
layerList.multipleSelectionEnabled = true;

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

selectedItems

Property
selectedItems Collection<ListItem>

A collection of selected ListItems representing operational layers selected by the user.

See also

selectionEnabled

Property
selectionEnabled Boolean
Deprecated since 4.29. Use selectionMode and dragEnabled instead.

Indicates whether list items may be selected by the user. Selected items may be reordered in the list by dragging gestures with the mouse or touch screen, or with arrow keys on the keyboard.

Selected items are available in the selectedItems property.

Default Value:false
See also
Example
layerList.selectionEnabled = true;

selectionMode

Property
selectionMode String
Since: ArcGIS Maps SDK for JavaScript 4.29 LayerList since 4.2, selectionMode added at 4.29.

Specifies the selection mode. Selected items are available in the selectedItems property.

Value Description
multiple Allows any number of items to be selected at once. This is useful when you want to apply an operation to multiple items at the same time.
none Disables selection. Use this when you want to prevent selecting items.
single Allows only one item to be selected at a time. If another item is selected, the previous selection is cleared. This is useful when you want to ensure that a maximum of one item is selected at a time.
single-persist Allows only one item to be selected at a time and prevents de-selection. Once an item is selected, it remains selected until another item is selected. This is useful when you want to ensure that there is always exactly one selected item.

Possible Values:"multiple"|"none"|"single"|"single-persist"

Default Value:"none"
See also
Example
layerList.selectionMode = "multiple";

view

Property
view MapView|SceneView

A reference to the MapView or SceneView. Set this to link the widget to a specific view.

viewModel

Property
viewModel LayerListViewModel

The view model for this widget. This is a class that contains all the logic (properties and methods) that controls this widget's behavior. See the LayerListViewModel class to access all properties and methods on the widget.

visibilityAppearance

Property
visibilityAppearance String
Since: ArcGIS Maps SDK for JavaScript 4.29 LayerList since 4.2, visibilityAppearance added at 4.29.

Determines the icons used to indicate visibility.

Value Description Example
default Displays view icons on the far side. Icons are hidden except on hover or if they have keyboard focus. See view-visible and view-hide calcite icons. visibilityAppearance-default
checkbox Displays checkbox icons on the near side. See check-square-f and square calcite icons. visibilityAppearance-checkbox

Possible Values:"default"|"checkbox"

Default Value:"default"
Example
layerList.visibilityAppearance = "checkbox";

visible

Inherited
Property
visible Boolean
Inherited from Widget

Indicates whether the widget is visible.

If false, the widget will no longer be rendered in the web document. This may affect the layout of other elements or widgets in the document. For example, if this widget is the first of three widgets associated to the upper right hand corner of the view UI, then the other widgets will reposition when this widget is made invisible. For more information, refer to the css display value of "none".

Default Value:true
Example
// Hides the widget in the view
widget.visible = false;

visibleElements

Property
visibleElements VisibleElements
Since: ArcGIS Maps SDK for JavaScript 4.15 LayerList since 4.2, visibleElements added at 4.15.

The visible elements that are displayed within the widget. This property provides the ability to turn individual elements of the widget's display on/off.

Example
layerList.visibleElements = {
  closeButton: false,
  collapseButton: true,
  errors: true,
  filter: true,
  heading: true,
  statusIndicators: true
};

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.

Accessor
String

A utility method used for building the value for a widget's class property.

Widget

Destroys the widget instance.

Widget
Boolean

Emits an event on the instance.

Widget
Boolean

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

Widget
Boolean

Returns true if a named group of handles exist.

Accessor
Boolean

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected).

Widget
Boolean

isRejected() may be used to verify if creating an instance of the class is rejected.

Widget
Boolean

isResolved() may be used to verify if creating an instance of the class is resolved.

Widget
Object

Registers an event handler on the instance.

Widget

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

Widget

This method is primarily used by developers when implementing custom widgets.

Widget

Removes a group of handles owned by the object.

Accessor
Object

This method is primarily used by developers when implementing custom widgets.

Widget

Renders widget to the DOM immediately.

Widget

This method is primarily used by developers when implementing custom widgets.

Widget

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

LayerList
Promise

when() may be leveraged once an instance of the class is created.

Widget

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.

classes

Inherited
Method
classes(classNames){String}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.7 Widget since 4.2, classes added at 4.7.

A utility method used for building the value for a widget's class property. This aids in simplifying css class setup.

Parameter
classNames String|String[]|Object
repeatable

The class names.

Returns
Type Description
String The computed class name.
Example
// .tsx syntax showing how to set css classes while rendering the widget

render() {
  const dynamicIconClasses = {
    [css.myIcon]: this.showIcon,
    [css.greyIcon]: !this.showIcon
  };

  return (
    <div class={classes(css.root, css.mixin, dynamicIconClasses)} />
  );
}

destroy

Inherited
Method
destroy()
Inherited from Widget

Destroys the widget instance.

emit

Inherited
Method
emit(type, event){Boolean}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.5 Widget 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

Inherited
Method
hasEventListener(type){Boolean}
Inherited from Widget

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");
}

isFulfilled

Inherited
Method
isFulfilled(){Boolean}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.19 Widget since 4.2, isFulfilled added at 4.19.

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected). If it is fulfilled, true will be returned.

Returns
Type Description
Boolean Indicates whether creating an instance of the class has been fulfilled (either resolved or rejected).

isRejected

Inherited
Method
isRejected(){Boolean}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.19 Widget since 4.2, isRejected added at 4.19.

isRejected() may be used to verify if creating an instance of the class is rejected. If it is rejected, true will be returned.

Returns
Type Description
Boolean Indicates whether creating an instance of the class has been rejected.

isResolved

Inherited
Method
isResolved(){Boolean}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.19 Widget since 4.2, isResolved added at 4.19.

isResolved() may be used to verify if creating an instance of the class is resolved. If it is resolved, true will be returned.

Returns
Type Description
Boolean Indicates whether creating an instance of the class has been resolved.

on

Inherited
Method
on(type, listener){Object}
Inherited from Widget

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

Parameters

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);
});

own

Inherited
Method
own(handleOrHandles)
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.24 Widget since 4.2, own added at 4.24.
Deprecated since 4.28 Use addHandles() instead.

Adds one or more handles which are to be tied to the lifecycle of the widget. The handles will be removed when the widget is destroyed.

const handle = reactiveUtils.when(
  () => !view.updating,
  () => {
    wkidSelect.disabled = false;
  },
  { once: true}
);

this.own(handle); // Handle gets removed when the widget is destroyed.
Parameter
handleOrHandles WatchHandle|WatchHandle[]

Handles marked for removal once the widget is destroyed.

postInitialize

Inherited
Method
postInitialize()
Inherited from Widget

This method is primarily used by developers when implementing custom widgets. Executes after widget is ready for rendering.

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");

render

Inherited
Method
render(){Object}
Inherited from Widget

This method is primarily used by developers when implementing custom widgets. It must be implemented by subclasses for rendering.

Returns
Type Description
Object The rendered virtual node.

renderNow

Inherited
Method
renderNow()
Inherited from Widget

Renders widget to the DOM immediately.

scheduleRender

Inherited
Method
scheduleRender()
Inherited from Widget

This method is primarily used by developers when implementing custom widgets. Schedules widget rendering. This method is useful for changes affecting the UI.

triggerAction

Method
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.

when

Inherited
Method
when(callback, errback){Promise}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.19 Widget since 4.2, when added at 4.19.

when() 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 instance of the class loads. The errback executes if the instance of the class fails to load.

Parameters
callback Function
optional

The function to call when the promise resolves.

errback Function
optional

The function to execute when the promise fails.

Returns
Type Description
Promise Returns a new promise for the result of callback.
Example
// Although this example uses the BasemapGallery widget, any class instance that is a promise may use when() in the same way
let bmGallery = new BasemapGallery();
bmGallery.when(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
});

Type Definitions

ListItemCreatedHandler

Type Definition
ListItemCreatedHandler(event)

Function definition for the listItemCreatedFunction property. See the example snippet in the listItemCreatedFunction documentation for more details.

Parameters
event Object

An object containing a list item created by the LayerList.

Specification
item ListItem

A list item created by the LayerList. You can modify the properties of this item to customize the text, actions, panel content, and visibility of the list item. See the documentation for the listItemCreatedFunction for more details.

VisibleElements

Type Definition
VisibleElements
Since: ArcGIS Maps SDK for JavaScript 4.15 LayerList since 4.2, VisibleElements added at 4.15.

The visible elements that are displayed within the widget. This provides the ability to turn individual elements of the widget's display on/off.

Properties
closeButton Boolean
optional
Default Value:false

Since 4.29 Indicates whether to display a close button in the header.

collapseButton Boolean
optional
Default Value:false

Since 4.29 Indicates whether to display a collapse button in the header.

errors Boolean
optional
Default Value:false

Since 4.25 Indicates whether layer load errors will be displayed.

filter Boolean
optional
Default Value:false

Since 4.29 Indicates whether to display a filter input box when then number of list items is equal to or greater than the value set in minFilterItems, allowing users to filter layers by their title.

flow Boolean
optional
Default Value:true

Since 4.29 Determines whether the widget should be shown within its built-in flow component or if the flow component should be excluded. The widget will be displayed within its original flow component if set to true. The flow component will be omitted from the widget if set to false. To place the widget into an existing Calcite flow component, set this property to false.

heading Boolean
optional
Default Value:false

Since 4.29 Indicates whether to display the widget heading. The heading text is "Layer List". The heading level can be set with the headingLevel.

statusIndicators Boolean
optional
Default Value:true

Indicates whether the status indicators will be displayed.

temporaryLayerIndicators Boolean
optional
Default Value:false

Since 4.29 Indicates whether temporary layer indicators will be displayed for layers with layer.persistenceEnabled set to false. A temporary icon will be displayed on the near side of the layer title.

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.

LayerList

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

The action clicked by the user.

item ListItem

The ListItem associated with the action.

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