Track

Provides a simple button that animates the View to the user's location when clicked. The view rotates based on device heading. 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.

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

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

The Track widget is only available in secure contexts, such as HTTPS. Note that localhost is considered "potentially secure" and can be used for easy testing in browsers that support Window.isSecureContext.

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

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

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Type	Summary	Class
String\|HTMLElement	The ID or node representing the DOM element containing the widget. more details	Widget
String	The name of the class. more details	Accessor
Object	An object used for setting optional position parameters. more details	Track
Boolean	Indicates whether the widget will automatically navigate the view to the user's position when a geolocation result is found. more details	Track
GoToOverride	This function provides the ability to override either the MapView goTo() or SceneView goTo() methods. more details	Track
Graphic	The graphic used to show the user's location on the map. more details	Track
String	The widget's default CSS icon class. more details	Track
String	The unique ID assigned to the widget when the widget is created. more details	Widget
String	The widget's default label. more details	Track
Number	Indicates the scale to set on the view when navigating to the position of the geolocated result, after a location is returned from the track event. more details	Track
Boolean	Indicates whether the widget is watching for new positions. more details	Track
Boolean	Indicates whether the widget will automatically rotate to the device heading based on the Geolocation APIs `GeolocationCoordinates.heading` property. more details	Track
MapView\|SceneView	A reference to the MapView or SceneView. more details	Track
TrackViewModel	The viewModel for this widget. more details	Track
Boolean	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

An object used for setting optional position parameters. Refer to the Geolocation API Specification for details on using these parameters.

Default Value:null

Example

const track = new Track({
  view: view,
  // Set optional position parameters
  geolocationOptions: {
    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 on the map.

Example

const trackWidget = new Track({
  // Assign the track widget to a view
  view: view,
  // Overwrite the default symbol used for the
  // graphic placed at the location of the user
  graphic: new Graphic ({
   symbol: {
     // autocasts as new SimpleMarkerSymbol()
     type: "simple-marker",
     size: "12px",
     color: "blue",
     // autocasts as new SimpleLineSymbol()
     outline: {
       color: "#efefef",
       width: "1.5px"
     }
   }
 })
});

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, after a location is returned from the track event.

By default, the view will navigate to a scale of 2500 for 3D and 4514 for 2D. To override the default in 2D, set the scale property and also set snapToZoom to false. For 2D views the value should be within the effectiveMinScale and effectiveMaxScale.

Default Value:null

Example

const mapView = new MapView({
  map: map,
  container: "viewDiv",
  // Turn off snapToZoom
  constraints: {
    snapToZoom: false
  }
});

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

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

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 the device heading based on the Geolocation APIs GeolocationCoordinates.heading property. The map will not rotate if the speed is 0, or if the device is unable to provide heading information.

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 viewModel 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

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

Method Details

addHandles(handleOrHandles, groupKey)inherited Since: ArcGIS API for JavaScript 4.25

Adds one or more handles which are to be tied to the lifecycle of the object. The handles will be removed when the object is destroyed.

// Manually manage handles
const handle = reactiveUtils.when(
  () => !view.updating,
  () => {
    wkidSelect.disabled = false;
  },
  { once: true }
);

// Handle gets removed when the object is destroyed.
this.addHandles(handle);

Parameters

handleOrHandles WatchHandle|WatchHandle []

Handles marked for removal once the object is destroyed.

groupKey *

optional

Key identifying the group to which the handles should be added. All the handles in the group can later be removed with Accessor.removeHandles(). If no key is provided the handles are added to a default group.

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.

hasHandles(groupKey){Boolean}inherited Since: ArcGIS API for JavaScript 4.25

Returns true if a named group of handles exist.

Parameter

groupKey *

optional

A group key.

Returns

Type	Description
Boolean	Returns `true` if a named group of handles exist.

Example

// Remove a named group of handles if they exist.
if (obj.hasHandles("watch-view-updates")) {
  obj.removeHandles("watch-view-updates");
}

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(handleOrHandles)inherited Since: ArcGIS API for JavaScript 4.24

Adds one or more handles which are to be tied to the lifecycle of the widget. The handles will be removed when the widget is destroyed.

const handle = reactiveUtils.when(
  () => !view.updating,
  () => {
    wkidSelect.disabled = false;
  },
  { once: true}
);

this.own(handle); // Handle gets removed when the widget is destroyed.

Parameter

handleOrHandles 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.

removeHandles(groupKey)inherited Since: ArcGIS API for JavaScript 4.25

Removes a group of handles owned by the object.

Parameter

groupKey *

optional

A group key or an array or collection of group keys to remove.

Example

obj.removeHandles(); // removes handles from default group

obj.removeHandles("handle-group");
obj.removeHandles("other-handle-group");

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. Only start the widget on a user gesture such as a click event.

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`.

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}	Fires after the start() method is called and a position is found. more details	Track
	{error: Error}	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

Geolocation coordinates 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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