Class: esri/widgets/Widget
Inheritance: Widget Accessor
Since: ArcGIS API for JavaScript 4.2

The base class for widgets. Each widget's presentation is separate from its properties, methods, and data.

The separation of core logic and presentation makes each widget highly customizable when working with other frameworks and libraries such as Bootstrap, React, and JQuery.

The properties and methods of each widget are handled in its viewModel property, which is an Accessor-based class. Since each view model class extends Accessor, all properties on the widget can be accessed using the methods outlined in the Working with properties topic.

This design allows developers to create new widgets and repurpose existing widgets with a third party framework. Separation of a widget's presentation and core logic also means developers can use the logic without having to render its UI components. More information about creating custom widgets is available in the Widget development Guide topic.

For information about gaining full control of widget styles, see the Styling topic.
See also:

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.

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String

The name of the class.

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Boolean

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

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String

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

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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.

destroyedBoolean

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

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.

Method Overview

NameReturn TypeSummaryClass
String

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

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more detailsWidget

Destroys the widget instance.

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Emits an event on the instance.

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String

The widget's label.

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Boolean

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

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Object

Registers an event handler on the instance.

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more detailsWidget

Widget teardown helper.

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more detailsWidget

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

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Object

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

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more detailsWidget

Renders widget to the DOM immediately.

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more detailsWidget

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

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more detailsWidget

Deprecated. Finalizes the creation of the widget.*

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more detailsWidget

Method Details

classes(classNames){String}
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]: !showIcon
  };

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

Destroys the widget instance.

emit(type, event)
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.

get(){String}inner

The widget's label.

This property is useful whenever the widget is controlled by another one (e.g., Expand)

Returns:
TypeDescription
String
hasEventListener(type){Boolean}

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}

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)

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()

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

render(){Object}

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()

Renders widget to the DOM immediately.

scheduleRender()

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

startup()
Deprecated
  • since version 4.2.

Deprecated. Finalizes the creation of the widget.

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