require(["esri/widgets/Track/TrackViewModel"], function(TrackVM) { /* code goes here */ });
Class: esri/widgets/Track/TrackViewModel
Inheritance: TrackViewModel Accessor
Since: ArcGIS API for JavaScript 4.0

Provides the logic for the Track widget, which animates the View to the user's location when clicked and tracks it as the location is updated.

The (geolocation) functionality 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.

See also:
Example:
var trackWidget = new Track({
  viewModel: {  // autocasts as new TrackViewModel()
    view: view,   // attaches the Track to the view
  }
}, "trackDiv");

Constructors

new TrackViewModel(properties)
Parameter:
properties Object
optional

See the properties for a list of all the properties that may be passed into the constructor.

Property Overview

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

The name of the class.

more details
more detailsAccessor
Object

The HTML5 Geolocation Position options for locating.

more details
more detailsTrackViewModel
Boolean

Indicates whether to navigate the view to the position and scale of the geolocated result.

more details
more detailsTrackViewModel
Graphic

The graphic used to show the user's location on the map.

more details
more detailsTrackViewModel
Number

The scale to set on the view when navigating to the position of the geolocated result.

more details
more detailsTrackViewModel
String

The current state of the widget.

more details
more detailsTrackViewModel
Boolean

Indicates whether new positions are being watched.

more details
more detailsTrackViewModel
MapView | SceneView

The view associated with the widget.

more details
more detailsTrackViewModel

Property Details

declaredClassStringreadonly inherited
Since: ArcGIS API for JavaScript 4.7

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

geolocationOptionsObject

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

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

Indicates whether to navigate the view to the position and scale of the geolocated result.

Default Value:true
graphicGraphic

The graphic used to show the user's location on the map.

Example:
var locateWidget = new Locate({
  viewModel: { // autocasts as new LocateViewModel()
    view: view,  // Assigns the locate 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
    })
  }
});
scaleNumber
Since: ArcGIS API for JavaScript 4.7

The scale to set on the view when navigating to the position of the geolocated result. If a scale value is not explicitly set, then the view will navigate to a default scale of 2500.

Default Value:null
stateStringreadonly

The current state of the widget.

Possible Values: disabled | ready | tracking | waiting

Default Value:disabled
trackingBooleanreadonly

Indicates whether new positions are being watched.

Default Value:false

The view associated with the widget.

Method Overview

NameReturn TypeSummaryClass

Emits an event on the instance.

more details
more detailsTrackViewModel
Boolean

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

more details
more detailsTrackViewModel
Object

Registers an event handler on the instance.

more details
more detailsTrackViewModel

When executed, tracking starts at the user's location.

more details
more detailsTrackViewModel

Stops tracking the user's location when executed.

more details
more detailsTrackViewModel

Method Details

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.

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);
});
start()

When executed, tracking starts at the user's location.

stop()

Stops tracking the user's location when executed.

Event Overview

NameTypeSummaryClass
{position: Object}

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

more details
more detailsTrackViewModel
{error: Error}

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

more details
more detailsTrackViewModel

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.

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