ESM: import LayerList from "@arcgis/core/widgets/LayerList.js";
CDN: const LayerList = await $arcgis.import("@arcgis/core/widgets/LayerList.js");
Class: @arcgis/core/widgets/LayerList
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.
Example
const 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"
}); new LayerList(properties)
Parameter
optionalSee the properties for a list of all the properties that may be passed into the constructor.
Example
// typical usage
const layerlist = new LayerList({
view
});Show inherited properties Hide inherited properties
Property DetailsSince: ArcGIS Maps SDK for JavaScript 4.30 LayerList since 4.2, catalogLayerList added at 4.30.
The CatalogLayerList widget instance that displays a catalog layer's dynamic group layer. The catalog layer list will be displayed as an expandable ListItem in the LayerList widget. This property is set when a catalog layer's dynamic group layer is expanded in the LayerList. Otherwise, it is null. This list item will only be displayed when catalog layers are loaded in the map and will be displayed as a child of the catalog layer. This property is useful for listening to the trigger-action event and managing selections in catalog layers.
Example
// Use reactiveUtils to respond to the layerList.catalogLayerList "trigger-action" event
reactiveUtils.on(
() => layerList.catalogLayerList,
"trigger-action",
async (event) => {
if (event.action.id === "add-layer") {
// Get the parent catalog layer
const parentCatalogLayer = catalogUtils.getCatalogLayerForLayer(event.item.layer);
// Get the footprint from the parent catalog layer
const footprint = parentCatalogLayer.createFootprintFromLayer(event.item.layer);
// Get the layer from the footprint
const layerFromFootprint = await parentCatalogLayer.createLayerFromFootprint(footprint);
// Add the layer to the map
map.add(layerFromFootprint);
// back out of the catalog layer list to the main layer list
layerList.openedLayers.pop();
}
}
);
// Use reactiveUtils to watch for a selected item in the layerList.catalogLayerList
reactiveUtils.watch(
() => layerList.catalogLayerList?.selectedItems.at(0)?.layer,
(layer) => {
// When a layer is selected log out its title
if (layer) {
console.log(layer.title);
}
}
);Since: ArcGIS Maps SDK for JavaScript 4.30 LayerList since 4.2, catalogOptions added at 4.30.
CatalogLayer specific properties. Catalog layers will display their dynamicGroupLayer as an expandable catalogLayerList in the LayerList widget. This list item will only be displayed when catalog layers with dynamic group layers are loaded in the map. These are the properties that are used to configure the catalogLayerList.
Default Value:""
Placeholder text used in the filter input box.
optionalDefault Value:null
A function that executes each time a ListItem is created.
optionalDefault Value:10
The minimum number of list items required to display the filter input box.
optionalDefault Value:"none"
The selection mode for the catalog layer list. See CatalogLayerList.selectionMode for more information.
optionalDefault Value:"default"
Determines the icons used to indicate visibility. See CatalogLayerList.visibilityAppearance for more information.
optionalDefault Value:null
The visible elements that are displayed within the catalog layer list.
Default Value:true
Indicates whether to display errors in the catalog layer list.
optionalDefault Value:false
Indicates whether to display the filter input box in the catalog layer list.
optionalDefault Value:true
Indicates whether to display status indicators in the catalog layer list.
optionalDefault Value:false
Indicates whether temporary layer indicators will be displayed. A temporary icon will be displayed on the near side of the layer title.
Default Value:null
Example
const layerList = new LayerList({
catalogOptions: {
listItemCreatedFunction: (event) => {
const { item } = event;
item.actionsSections = [
[
{
title: "Add layer to map",
icon: "add-layer",
id: "add-layer"
}
]
];
},
selectionMode: "single",
visibleElements: {
filter: true
}
},
view,
}); 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.
Example
layerList.collapsed = true;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"
});Inherited
Property declaredClass Stringreadonly
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 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.
Example
layerList.dragEnabled = true; 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.
Example
layerList.filterPlaceholder = "Filter layers";Since: ArcGIS Maps SDK for JavaScript 4.32 LayerList since 4.2, filterPredicate added at 4.32.
Specifies a function to handle filtering list items.
Example
layerList.filterPredicate = (item) => item.title.toLowerCase().includes("streets"); 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.
Example
reactiveUtils.watch(
() => layerList.filterText,
(filterText) => console.log(filterText)
); 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.
Example
layerList.headingLevel = 3;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).
Inherited
Property id String
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.
Since: ArcGIS Maps SDK for JavaScript 4.30 LayerList since 4.2, knowledgeGraphOptions added at 4.30.
KnowledgeGraphLayer specific properties. Knowledge graph layers will display sublayer tables as an expandable tableList in the LayerList widget. This tables list item will only be displayed when knowledge graph layers with tables are loaded in the map. These are the properties that are used to configure the tableList.
Default Value:""
Placeholder text used in the filter input box.
optionalDefault Value:null
A function that executes each time a ListItem is created.
optionalDefault Value:10
The minimum number of list items required to display the filter input box.
optionalDefault Value:"none"
The selection mode for the table list. See TableList.selectionMode for more information.
Possible Values:"multiple"|"none"|"single"|"single-persist"
optionalDefault Value:null
The visible elements that are displayed within the table list.
Default Value:true
Indicates whether to display errors in the table list.
optionalDefault Value:false
Indicates whether to display the filter input box in the table list.
optionalDefault Value:true
Indicates whether to display status indicators in the table list.
Default Value:null
Example
layerList.knowledgeGraphOptions = {
filterPlaceholder: "Filter tables",
listItemCreatedFunction: (event) => {
const { item } = event;
item.actionsSections = [
[
{
icon: "table",
id: "open-table",
title: "Show table"
},
{
icon: "information",
id: "information",
title: "Show information"
}
]
];
},
minFilterItems: 1,
visibleElements: {
errors: true,
filter: true,
statusIndicators: true
}
}Since: ArcGIS Maps SDK for JavaScript 4.7 LayerList since 4.2, label added at 4.7.
The widget's default label.
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 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.
Example
layerList.dragEnabled = true;
layerList.minDragEnabledItems = 5; 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.
Example
layerList.visibleElements.filter = true;
layerList.minFilterItems = 5;Since: ArcGIS Maps SDK for JavaScript 4.31 LayerList since 4.2, openedLayers added at 4.31.
A collection of Layers that are opened in a catalogLayerList or tableList flow item. This property is useful for backing out of the catalog layer list or table list programmatically to the parent layer list.
Example
// back out of the catalog layer list to the main layer list
layerList.openedLayers.pop();A collection of ListItems representing operational layers. To hide layers from the LayerList widget, set the listMode property on the layer(s) to hide.
A collection of selected ListItems representing operational layers selected by the user.
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"
Example
layerList.selectionMode = "multiple";Since: ArcGIS Maps SDK for JavaScript 4.30 LayerList since 4.2, tableList added at 4.30.
The TableList widget instance that displays the tables associated with a KnowledgeGraphLayer. The table list will be displayed as an expandable ListItem in the LayerList widget. This property is set when a knowledge graph layer's tables ListItem is expanded in the LayerList. Otherwise, it is null. This list item will only be displayed when knowledge graph layers with tables are loaded in the map and will be displayed as a child of the knowledge graph layer. This property is useful for listening to the trigger-action event and managing selections in knowledge graph tables.
Example
// Use reactiveUtils to respond to the layerList.tableList "trigger-action" event
reactiveUtils.on(
() => layerList.tableList,
"trigger-action",
(event) => {
if (event.action.id === "open-table") {
// Open the table in the FeatureTable widget
featureTable.layer = event.item.layer;
// Back out of the table list to the layer list
layerList.openedLayers.pop();
}
}
);
// Use reactiveUtils to watch for a selected item in the layerList.tableList
reactiveUtils.watch(
() => layerList.tableList?.selectedItems.at(0)?.layer,
(layer) => {
// When a layer is selected log out its title
if (layer) {
console.log(layer.title);
}
}
);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 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.
Possible Values:"default" |"checkbox"
Example
layerList.visibilityAppearance = "checkbox";Inherited
Property visible Boolean
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".
Example
// Hides the widget in the view
widget.visible = false;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 = {
catalogLayerList: true,
closeButton: false,
collapseButton: true,
errors: true,
filter: true,
heading: true,
statusIndicators: true
};Show inherited methods Hide inherited methods
Method DetailsInherited
Method addHandles(handleOrHandles, groupKey)
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
Handles marked for removal once the object is destroyed.
groupKey *
optionalKey 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.
Inherited
Method classes(classNames){String}
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.
Returns
Type Description String The computed class name.Example
// .tsx syntax showing how to set css classes while rendering the widget
render() {
const dynamicClasses = {
[css.flip]: this.flip,
[css.primary]: this.primary
};
return (
<div class={classes(css.root, css.mixin, dynamicClasses)} />
);
}Inherited
Method destroy()
Destroys the widget instance.
Inherited
Method emit(type, event){Boolean}
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
The name of the event.
optionalThe event payload.
Returns
Type Description Booleantrue if a listener was notified
Inherited
Method hasEventListener(type){Boolean}
Indicates whether there is an event listener on the instance that matches the provided event name.
Returns
Type Description Boolean Returns true if the class supports the input event.Inherited
Method hasHandles(groupKey){Boolean}
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 *
optionalA group key.
Returns
Type Description Boolean Returnstrue 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");
}Inherited
Method isFulfilled(){Boolean}
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).Inherited
Method isRejected(){Boolean}
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.Inherited
Method isResolved(){Boolean}
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.Inherited
Method on(type, listener){Object}
Registers an event handler on the instance. Call this method to hook an event with a listener.
Returns
Type Description Object Returns an event handler with aremove() 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);
});Inherited
Method postInitialize()
Executes after widget is ready for rendering.
Inherited
Method removeHandles(groupKey)
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 *
optionalA 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");Inherited
Method render(){Object}
This method is implemented by subclasses for rendering.
Returns
Type Description Object The rendered virtual node.Inherited
Method renderNow()
Renders widget to the DOM immediately.
Inherited
Method scheduleRender()
Schedules widget rendering. This method is useful for changes affecting the UI.
Inherited
Method when(callback, errback){Promise}
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
optionalThe function to call when the promise resolves.
optionalThe function to execute when the promise fails.
Returns
Type Description Promise Returns a new Promise for the result ofcallback.
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
}); FilterPredicate(item)
Specifies a function to handle filtering list items.
Parameter
A list item created by the LayerList.
ListItemCreatedHandler(event)
Function definition for the listItemCreatedFunction property. See the example snippet in the listItemCreatedFunction documentation for more details.
Parameters
An object containing a list item created by the LayerList.
Specification
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 Accessor
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.
Default Value:true
Since 4.30 Indicates whether to display the catalogLayerList.
Default Value:false
Since 4.29 Indicates whether to display a close button in the header.
Default Value:false
Since 4.29 Indicates whether to display a collapse button in the header.
Default Value:false
Since 4.25 Indicates whether to display layers with load errors.
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.
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.
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.
Default Value:true
Indicates whether the status indicators will be displayed.
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.
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.
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