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
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 icon font.

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
String

Indicates the style of the legend.

more details
more detailsLegend
MapView | SceneView

A reference to the MapView or SceneView.

more details
more detailsLegend

Property Details

The ID or node representing the DOM element containing the widget. This property can only be set once.

declaredClassStringreadonly inherited
Since: ArcGIS API for JavaScript 4.7

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

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

iconClassStringreadonly
Since: ArcGIS API for JavaScript 4.7

The widget's default icon font.

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.

labelStringreadonly
Since: ArcGIS API for JavaScript 4.7

The widget's default label.

layerInfosObject[]

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.

styleString
Since: ArcGIS API for JavaScript 4.7
beta

Indicates the style of the legend. The style determines the legend's layout and behavior. See the table below for a list of possible values.

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 is 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.
Default Value:classic

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

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

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.

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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

Deprecated. Finalizes the creation of the widget.*

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.

Prior to version 4.7, there were various approaches towards setting CSS classes. These were dependant upon variables, such as whether the classes were:

  • a single static class,
  • multiple static classes, or
  • dynamic classes.

This helper method takes all of these approaches into account and simplifies it to use one single pattern to accommodate these multiple approaches.

Parameter:
classNames Array<(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)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

The event payload.

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:
type String

The name of event 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.
PropertyTypeDescription
removeFunctionWhen called, removes the listener from the event.
See also:
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.

startup()inherited
Deprecated
  • since version 4.2.

Deprecated. Finalizes the creation of the widget.

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