Widget
esri/widgets/WidgetThe 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.
Property Overview
| Name | Type | Summary | Class | |
|---|---|---|---|---|
| String|HTMLElement | The ID or node representing the DOM element containing the widget. more details | more details | Widget | |
| String | The name of the class. more details | more details | Accessor | |
| Boolean | When | more details | Widget | |
| String | The unique ID assigned to the widget when the widget is created. more details | more details | Widget | |
| String | The widget's label. more details | more details | Widget |
Property Details
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" });
- Since: ArcGIS API for JavaScript 4.7
The name of the class. The declared class name is formatted as
esri.folder.className.
- destroyed Boolean
When
true, this property indicates whether the widget has been destroyed.
- 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.
- label StringSince: ArcGIS API for JavaScript 4.11
The widget's label.
This property is useful whenever the widget is controlled by another one (e.g. Expand)
Method Overview
| Name | Return Type | Summary | Class | |
|---|---|---|---|---|
| String | A utility method used for building the value for a widget's | more details | Widget | |
Destroys the widget instance. more details | more details | Widget | ||
| Boolean | Emits an event on the instance. more details | more details | Widget | |
| Boolean | Indicates whether there is an event listener on the instance that matches the provided event name. more details | more details | Widget | |
| Object | Registers an event handler on the instance. more details | more details | Widget | |
Widget teardown helper. more details | more details | Widget | ||
This method is primarily used by developers when implementing custom widgets. more details | more details | Widget | ||
| Object | This method is primarily used by developers when implementing custom widgets. more details | more details | Widget | |
Renders widget to the DOM immediately. more details | more details | Widget | ||
This method is primarily used by developers when implementing custom widgets. more details | more details | Widget |
Method Details
- classes(classNames){String}Since: ArcGIS API for JavaScript 4.7
A utility method used for building the value for a widget's
classproperty. This aids in simplifying CSS class setup.Parameter:repeatable The class names.
Returns:Type Description String The computed class name. 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()
Destroys the widget instance.
- emit(type, event){Boolean}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 StringThe name of the event.
event ObjectoptionalThe event payload.
Returns:Type Description Boolean trueif a listener was notified
- hasEventListener(type){Boolean}
Indicates whether there is an event listener on the instance that matches the provided event name.
Parameter:type StringThe name of the event.
Returns:Type Description Boolean Returns 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:A event type, or an array of event types, to listen for.
listener FunctionThe function to call when the event is fired.
Returns:Type Description Object Returns an event handler with a remove()method that can 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(handles)
Widget teardown helper. Any handles added to it will be automatically removed when the widget is destroyed.
Parameter:handles WatchHandle|WatchHandle[]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:Type Description Object The 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.