BasemapLayerList

AMD: require(["esri/widgets/BasemapLayerList"], (BasemapLayerList) => { /* code goes here */ });
ESM: import BasemapLayerList from "@arcgis/core/widgets/BasemapLayerList";
Class: esri/widgets/BasemapLayerList
Inheritance: BasemapLayerList Widget Accessor
Since: ArcGIS Maps SDK for JavaScript 4.13

The BasemapLayerList widget provides a way to display a list of Basemap layers and switch on/off their visibility. Base layers and reference layers are divided into separate sections. When editing is enabled, layers can be reordered by dragging and dropping between the lists and the title can be edited.

BasemapLayerList is very similar to our LayerList widget. See below samples for code inspiration:
Sample - LayerList widget
Sample - LayerList widget with actions

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

Constructors

new BasemapLayerList(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 BasemapLayerList = new BasemapLayerList({
  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
Collection<ListItem>

A collection of ListItems representing the baseLayers.

more details
BasemapLayerList
ListItemCreatedHandler

Specifies a function that accesses each ListItem representing a base layer.

more details
BasemapLayerList
String

The current basemap's title.

more details
BasemapLayerList
String|HTMLElement

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

more details
Widget
String

The name of the class.

more details
Accessor
Boolean

Indicates whether the basemap’s title, layer order and layer grouping can be edited by the user.

more details
BasemapLayerList
Number

Indicates the heading level to use for the widget title (i.e.

more details
BasemapLayerList
String

The widget's default CSS icon class.

more details
BasemapLayerList
String

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

more details
Widget
String

The widget's default label.

more details
BasemapLayerList
Boolean

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

more details
BasemapLayerList
Collection<ListItem>

A collection of ListItems representing the referenceLayers.

more details
BasemapLayerList
ListItemCreatedHandler

Specifies a function that accesses each ListItem representing a reference layer.

more details
BasemapLayerList
Collection<ListItem>

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

more details
BasemapLayerList
MapView|SceneView

A reference to the MapView or SceneView.

more details
BasemapLayerList
BasemapLayerListViewModel

The view model for this widget.

more details
BasemapLayerList
Boolean

Indicates whether the widget is visible.

more details
Widget
VisibleElements

The visible elements that are displayed within the widget.

more details
BasemapLayerList

Property Details

baseItems Collection<ListItem>readonly

A collection of ListItems representing the baseLayers.

baseListItemCreatedFunction ListItemCreatedHandler

Specifies a function that accesses each ListItem representing a base layer. Each list item's modifiable properties can be updated within. Actions can be added to list items using the actionsSections property of the ListItem.

Example
let bmLayerList = new BasemapLayerList({
  view: view,
  editingEnabled: true,
  baseListItemCreatedFunction: function(event){
    baseListItem = event.item;
    if(baseListItem.title === "World Imagery_01"){
      // clean up title
      baseListItem.title = "World Imagery";
      // open the baseList item
      baseListItem.open = true;
    }
  }
})
basemapTitle String

The current basemap's title.

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 cases 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 Stringreadonly inherited

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

editingEnabled Boolean

Indicates whether the basemap’s title, layer order and layer grouping can be edited by the user. Any edits made will only be shown locally and will not be saved.

Default Value:false
Example
// to enable editing
basemapLayerList.editingEnabled = true;
headingLevel Number
Since: ArcGIS Maps SDK for JavaScript 4.20

Indicates the heading level to use for the widget title (i.e. "Basemap"). By default, this is rendered as a level 2 heading (e.g. <h2>Basemap</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
// the widget title will render as an <h3>
basemapLayerList.headingLevel = 3;
iconClass String

The widget's default CSS icon class.

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 String

The widget's default label.

multipleSelectionEnabled Boolean

Indicates whether more than one list item may be selected by the user at a single time. Selected items are available in the selectedItems property.

Default Value:false
See also
Example
basemapLayerList.multipleSelectionEnabled = true;
referenceItems Collection<ListItem>readonly

A collection of ListItems representing the referenceLayers.

referenceListItemCreatedFunction ListItemCreatedHandler

Specifies a function that accesses each ListItem representing a reference layer. Each list item's modifiable properties can be updated within. Actions can be added to list items using the actionsSections property of the ListItem.

Example
let bmLayerList = new BasemapLayerList({
  view: view,
  editingEnabled: true,
  referenceListItemCreatedFunction: function(event){
    referenceListItem = event.item;
    if(referenceListItem.title === "World Imagery_01_reference_layer"){
      // clean up title
      referenceListItem.title = "Reference layer";
      // open the baseList item
      referenceListItem.open = true;
    }
  }
})
selectedItems Collection<ListItem>

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

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

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 BasemapLayerListViewModel class to access all properties and methods on the widget.

visible Boolean inherited

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 VisibleElements
Since: ArcGIS Maps SDK for JavaScript 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
basemapLayerList.visibleElements = {
  statusIndicators: false,
  baseLayers: false,
  referenceLayers: false,
  errors: 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.

more details
Accessor
String

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

more details
Widget

Destroys the widget instance.

more details
Widget
Boolean

Emits an event on the instance.

more details
Widget
Boolean

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

more details
Widget
Boolean

Returns true if a named group of handles exist.

more details
Accessor
Boolean

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

more details
Widget
Boolean

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

more details
Widget
Boolean

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

more details
Widget
Object

Registers an event handler on the instance.

more details
Widget

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

more details
Widget

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

more details
Widget

Removes a group of handles owned by the object.

more details
Accessor
Object

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

more details
Widget

Renders widget to the DOM immediately.

more details
Widget

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

more details
Widget

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

more details
BasemapLayerList
Promise

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

more details
Widget

Method Details

addHandles(handleOrHandles, groupKey)inherited
Since: ArcGIS Maps SDK 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.

classes(classNames){String}inherited

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.
See also
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

Destroys the widget instance.

emit(type, event){Boolean}inherited

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(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
Type Description
Boolean Returns true if the class supports the input event.
hasHandles(groupKey){Boolean}inherited
Since: ArcGIS Maps SDK 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");
}
isFulfilled(){Boolean}inherited
Since: ArcGIS Maps SDK for JavaScript 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(){Boolean}inherited
Since: ArcGIS Maps SDK for JavaScript 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(){Boolean}inherited
Since: ArcGIS Maps SDK for JavaScript 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(type, listener){Object}inherited

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(handleOrHandles)inherited
Since: ArcGIS Maps SDK for JavaScript 4.24

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

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

removeHandles(groupKey)inherited
Since: ArcGIS Maps SDK 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");
render(){Object}inherited

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

Renders widget to the DOM immediately.

scheduleRender()inherited

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

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(callback, errback){Promise}inherited
Since: ArcGIS Maps SDK for JavaScript 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(event)

Function definition for the baseListItemCreatedFunction and referenceListItemCreatedFunction properties. See the example snippets in the documentations for those properties 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

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
statusIndicators Boolean
optional

Indicates whether to the status indicators will be displayed. Default is true.

baseLayers Boolean
optional

Indicates whether to the base layers will be displayed. Default is true.

referenceLayers Boolean
optional

Indicates whether to the reference layers will be displayed. Default is true.

errors Boolean
optional

Since 4.25 Indicates whether layer load errors will be displayed. Default is false.

Event Overview

Name Type Summary Class
{action: ActionButton,ActionToggle,item: ListItem}

Fires after the user clicks on an action or action toggle inside the BasemapLayerList widget.

more details
BasemapLayerList

Event Details

trigger-action

Fires after the user clicks on an action or action toggle inside the BasemapLayerList 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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