Track

Provides a simple button that animates the View to the user's location when clicked. The view rotates according to the direction where the tracked device is heading towards. While tracking, the default button looks like the following:

track-button

You can use the view's DefaultUI to add widgets to the view's user interface via the ui property on the view. The snippet below demonstrates this.

The Track widget is not supported on insecure origins. To use it, switch your application to a secure origin, such as HTTPS. Note that localhost is considered "potentially secure" and can be used for easy testing in browsers that supports Window.isSecureContext (currently Chrome and Firefox).

As of version 4.2, the Track Button no longer displays in non-secure web apps. At version 4.1 this only applied to Google Chrome.

For additional information regarding this, visit the ArcGIS blog, Increased web API security in Google Chrome.

Known Limitation

The Track widget does not work concurrently with the Locate widget. Only one of the widgets can be used at a time.

See also:

Example:

let trackWidget = new Track({
  view: view
});

view.ui.add(trackWidget, "top-left");

Constructors

new Track(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
let track = new Track({
  view: view
});

Property Overview

Any properties can be set, retrieved or listened to. See the Working with Properties topic.

Show inherited properties

Hide inherited properties

Type	Summary	Class
String\|HTMLElement	more details The ID or node representing the DOM element containing the widget.	more details	Widget
String	more details The name of the class.	more details	Accessor
Object	more details The HTML5 Geolocation Position options for locating.	more details	Track
Boolean	more details Indicates whether the widget will automatically navigate the view to the user's position when a geolocation result is found.	more details	Track
GoToOverride	more details This function provides the ability to override either the MapView goTo() or SceneView goTo() methods.	more details	Track
Graphic	more details The graphic used to show the user's location in the view.	more details	Track
String	more details The widget's default CSS icon class.	more details	Track
String	more details The unique ID assigned to the widget when the widget is created.	more details	Widget
String	more details The widget's default label.	more details	Track
Number	more details Indicates the scale to set on the view when navigating to the position of the geolocated result once a location is returned from the track event.	more details	Track
Boolean	more details Indicates whether the widget is watching for new positions.	more details	Track
Boolean	more details Indicates whether the widget will automatically rotate to user's direction.	more details	Track
MapView\|SceneView	more details A reference to the MapView or SceneView.	more details	Track
TrackViewModel	more details The view model for this widget.	more details	Track
Boolean	more details Indicates whether the widget is visible.	more details	Widget

Property Details

container String|HTMLElement inherited

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"
});

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.

geolocationOptions Object

The HTML5 Geolocation Position options for locating. Refer to Geolocation API Specification for details.

Default Value:{ maximumAge: 0, timeout: 15000, enableHighAccuracy: true }

goToLocationEnabled Boolean

Indicates whether the widget will automatically navigate the view to the user's position when a geolocation result is found. Set to false to disable this behavior, leaving full control to the developer.

Default Value:true

goToOverride GoToOverride Since: ArcGIS API for JavaScript 4.8

This function provides the ability to override either the MapView goTo() or SceneView goTo() methods.

See also:

Example:

// The following snippet uses the Search widget but can be applied to any
// widgets that support the goToOverride property.
search.goToOverride = function(view, goToParams) {
  goToParams.options.duration = updatedDuration;
  return view.goTo(goToParams.target, goToParams.options);
};

graphic Graphicautocast

The graphic used to show the user's location in the view.

Example:

let trackWidget = new Track({
  view: view,  // Assigns the track widget to a view
    graphic: new Graphic({
      symbol: { type: "simple-marker" }  // Overwrites the default symbol used for the
      // graphic placed at the location of the user when found
    })
});

iconClass String Since: ArcGIS API for JavaScript 4.7

The widget's default CSS icon class.

id String inherited

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.

scale Number Since: ArcGIS API for JavaScript 4.7

Indicates the scale to set on the view when navigating to the position of the geolocated result once a location is returned from the track event. If a scale value is not explicitly set, then the view will navigate to a default scale of 2500. For 2D views the value should be within the effectiveMinScale and effectiveMaxScale.

Default Value:null

Example:

mapView.watch("scale", function (currentScale){
  console.log("scale: %s", currentScale);
});

mapView.when(function(){
  // Create an instance of the Track widget
  let track = new Track({
    view: mapView,
    scale: 5000
  });

  // and add it to the view's UI
  mapView.ui.add(track, "top-left");

  track.start();

  track.on("track", function(trackEvent){
    console.log(trackEvent);
    console.log("track: %s", mapView.scale);
  })
});

tracking Booleanreadonly

Indicates whether the widget is watching for new positions.

Default Value:false

useHeadingEnabled Boolean Since: ArcGIS API for JavaScript 4.6

Indicates whether the widget will automatically rotate to user's direction. Set to false to disable this behavior.

Default Value:true

view MapView|SceneView

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

viewModel TrackViewModelautocast

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

visible Boolean inherited

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".

Default Value:true

Example:

// Hides the widget in the view
widget.visible = false;

Method Overview

Show inherited methods

Hide inherited methods

Return Type	Summary	Class
String	more details A utility method used for building the value for a widget's `class` property.	more details	Widget
	more details Destroys the widget instance.	more details	Widget
Boolean	more details Emits an event on the instance.	more details	Widget
Boolean	more details Indicates whether there is an event listener on the instance that matches the provided event name.	more details	Widget
Boolean	more details `isFulfilled()` may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected).	more details	Widget
Boolean	more details `isRejected()` may be used to verify if creating an instance of the class is rejected.	more details	Widget
Boolean	more details `isResolved()` may be used to verify if creating an instance of the class is resolved.	more details	Widget
Object	more details Registers an event handler on the instance.	more details	Widget
	more details Widget teardown helper.	more details	Widget
	more details This method is primarily used by developers when implementing custom widgets.	more details	Widget
Object	more details This method is primarily used by developers when implementing custom widgets.	more details	Widget
	more details Renders widget to the DOM immediately.	more details	Widget
	more details This method is primarily used by developers when implementing custom widgets.	more details	Widget
	more details When executed, the widget will start tracking the user's location.	more details	Track
	more details Stops tracking the user's location when executed.	more details	Track
Promise	more details `when()` may be leveraged once an instance of the class is created.	more details	Widget

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:

Type	Description
String	The computed class name.

See also:

Guide - Widget development (rendering)

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:

Type	Description
Boolean	`true` 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:

Type	Description
Boolean	Returns true if the class supports the input event.

isFulfilled(){Boolean}inherited Since: ArcGIS API for JavaScript 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).

isRejected(){Boolean}inherited Since: ArcGIS API for JavaScript 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.

isResolved(){Boolean}inherited Since: ArcGIS API for JavaScript 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.

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|String []

An event or an array of events to listen for.

listener Function

The function to call when the event fires.

Returns:

Type Description

Object

Returns an event handler with a remove() 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);
});

own(handles)inherited

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()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:

Type	Description
Object	The 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.

start()

When executed, the widget will start tracking the user's location.

stop()

Stops tracking the user's location when executed.

when(callback, errback){Promise}inherited Since: ArcGIS API for JavaScript 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:

callback Function

optional

The function to call when the promise resolves.

errback Function

optional

The function to execute when the promise fails.

Returns:

Type	Description
Promise	Returns a new promise for the result of `callback` that may be used to chain additional functions.

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
});

Event Overview

Name	Type	Summary	Class
	{position: Object}	more details Fires after the start() method is called and a position is found.	more details	Track
	{error: Error}	more details Fires after the start() method is called and an error is returned.	more details	Track

Event Details

track

Fires after the start() method is called and a position is found.

Property:

position Object

Geoposition returned from the Geolocation API.

track-error

Fires after the start() method is called and an error is returned.

Property:

error Error

The Error object returned if an error occurred while tracking.

ArcGIS API for JavaScriptAPI Reference

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