Skip To ContentArcGIS for DevelopersSign In Dashboard
require(["esri/widgets/Legend"], function(Legend) { /* code goes here */ });
Class: esri/widgets/Legend
Inheritance: Legend Widget Accessor
Since: ArcGIS API for JavaScript 4.0

The Legend widget displays labels and symbols for layers in a map. Labels and their corresponding symbols depend on the values set in the Renderer of the layer. The legend will only display layers and sublayers that are visible in the view.

The legend automatically updates when

  • the visibility of a layer or sublayer changes
  • a layer is added or removed from the map
  • a layer's renderer, opacity, or title is changed
  • the legendEnabled property is changed (set to true or false on the layer)

widgets-legend-basic

You can use the view's DefaultUI to add widgets to the view's user interface via the ui property on the view.

Known Limitations

For information about gaining full control of widget styles, see the Styling topic.
See also:
Example:
var legend = new Legend({
  view: view,
  layerInfos: [{
    layer: featureLayer,
    title: "Legend"
  }]
});

view.ui.add(legend, "bottom-right");

Constructors

new Legend(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
var legend = new Legend({
  view: view
});

Property Overview

Any properties can be set, retrieved or listened to. See the Working with Properties topic.
NameTypeSummaryClass
Collection<ActiveLayerInfo>

Collection of ActiveLayerInfo objects used by the legend view to display data in the legend.

more details
more detailsLegend
Boolean

Indicates whether to show the Basemap layers in the Legend.

more details
more detailsLegend
String|HTMLElement

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

more details
more detailsWidget
String

The name of the class.

more details
more detailsAccessor
Boolean

When true, this property indicates whether the widget has been destroyed.

more details
more detailsWidget
String

The widget's default CSS icon class.

more details
more detailsLegend
String

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

more details
more detailsWidget
String

The widget's default label.

more details
more detailsLegend
Object[]

Specifies a subset of the layers to display in the legend.

more details
more detailsLegend
Object|String

Indicates the style of the legend.

more details
more detailsLegend
MapView|SceneView

A reference to the MapView or SceneView.

more details
more detailsLegend
LegendViewModel

The view model for this widget.

more details
more detailsLegend

Property Details

Autocasts from Object[]

Collection of ActiveLayerInfo objects used by the legend view to display data in the legend. The legend widget watches this property to hide or display the layer's legend when an ActiveLayerInfo is removed from or added to this collection.

basemapLegendVisible Boolean

Indicates whether to show the Basemap layers in the Legend.

Default Value:false
Example:
legend.basemapLegendVisible = 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 cases when working with widgets.

Examples:
// Create the HTML div element programatically 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
Since: ArcGIS API for JavaScript 4.7

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

destroyed Boolean inherited

When true, this property indicates whether the widget has been destroyed.

iconClass String
Since: ArcGIS API for JavaScript 4.7

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
Since: ArcGIS API for JavaScript 4.7

The widget's default label.

layerInfos Object[]

Specifies a subset of the layers to display in the legend. If this property is not set, all layers in the map will display in the legend. Objects in this array are defined with the properties listed below.

Properties:
title String
optional

Specifies a title for the layer to display above its symbols and descriptions. If no title is specified the service name is used.

layer Layer

A layer to display in the legend.

Since: ArcGIS API for JavaScript 4.7

Indicates the style of the legend. The style determines the legend's layout and behavior. You can either specify a string or an object to indicate the style. The known string values are the same values listed in the table within the type property.

Properties:
type String

Specifies the style of the legend. There are two possible values listed in the table below:

ValueDescription
classicThe legend has a portrait orientation. The user can scroll vertically when many elements are included in the legend's content.
cardIn wide views, the legend has a landscape orientation that allows users to scroll horizontally to view all legend elements. This style can be responsive, making it ideal for mobile web apps. In smaller views, the legend collapses to occupy less space. One element is shown at a time in a card-style layout, which the user can navigate horizontally.
layout String
optional
Default Value:stack

When a card type is specified, you can specify one of the following layout options.

ValueDescription
autoThis layout is responsive so that in wide views the legend has a side-by-side layout, and a stack layout in smaller (mobile) views.
side-by-sideThe legend has a landscape orientation that allows users to scroll horizontally to view multiple legend cards at a time.
stackThe legend cards are stacked, which conserves space, but restricts the user to seeing only one card at a time.
Default Value:classic
Examples:
// renders the legend in the card style with a "stack" layout
legend.style = "card";
// renders the legend in the card style with a responsive
// layout that toggles between "stack" and "side-by-side"
legend.style = {
  type: "card",
  layout: "auto"
};
// renders the legend in the classic layout
legend.style = "classic";

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

Method Overview

NameReturn TypeSummaryClass
String

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

more details
more detailsWidget

Destroys the widget instance.

more details
more detailsWidget
Boolean

Emits an event on the instance.

more details
more detailsWidget
Boolean

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

more details
more detailsWidget
Object

Registers an event handler on the instance.

more details
more detailsWidget

Widget teardown helper.

more details
more detailsWidget

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

more details
more detailsWidget
Object

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

more details
more detailsWidget

Renders widget to the DOM immediately.

more details
more detailsWidget

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

more details
more detailsWidget

Method Details

classes(classNames){String}inherited
Since: ArcGIS API for JavaScript 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:
TypeDescription
StringThe 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
Since: ArcGIS API for JavaScript 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:
TypeDescription
Booleantrue 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:
TypeDescription
BooleanReturns true if the class supports the input event.
on(type, listener){Object}inherited

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

Parameters:

A event type, or an array of event types, to listen for.

listener Function

The function to call when the event is fired.

Returns:
TypeDescription
ObjectReturns an event handler with a remove() method that can be called to stop listening for the event(s).
PropertyTypeDescription
removeFunctionWhen 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(handles)inherited

Widget teardown helper. Any handles added to it will be automatically removed when the widget is destroyed.

Parameter:

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.

render(){Object}inherited

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

Returns:
TypeDescription
ObjectThe 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.

API Reference search results

NameTypeModule
Loading...