TrackViewModel

AMD: require(["esri/widgets/Track/TrackViewModel"], (TrackVM) => { /* code goes here */ });
ESM: import TrackVM from "@arcgis/core/widgets/Track/TrackViewModel";
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 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.

See also
Example
let 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.
Show inherited properties Hide inherited properties
Name Type Summary Class
String

The name of the class.

more details
Accessor
Object

An object used for setting optional position parameters.

more details
TrackViewModel
Boolean

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

more details
TrackViewModel
GoToOverride

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

more details
TrackViewModel
Graphic

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

more details
TrackViewModel
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
TrackViewModel
String

The current state of the widget.

more details
TrackViewModel
Boolean

Indicates whether new positions are being watched.

more details
TrackViewModel
MapView|SceneView

The view associated with the widget.

more details
TrackViewModel

Property Details

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 paramters.

Default Value:null
Example
const track = new Track({
  view: view,
  // Set optional position paramters
  geolocationOptions: {
    maximumAge: 0,
    timeout: 15000,
    enableHighAccuracy: true
  }
});
goToLocationEnabled Boolean

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

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 Graphic

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"
     }
   }
 })
});
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
state Stringreadonly

The current state of the widget.

Possible Values:"disabled"|"ready"|"tracking"|"waiting"

Default Value:disabled
tracking Booleanreadonly

Indicates whether new positions are being watched.

Default Value:false

The view associated with the widget.

Method Overview

Show inherited methods Hide inherited methods
Name Return Type Summary Class

Adds one or more handles which are to be tied to the lifecycle of the object.

more details
Accessor
Boolean

Emits an event on the instance.

more details
TrackViewModel
Boolean

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

more details
TrackViewModel
Boolean

Returns true if a named group of handles exist.

more details
Accessor
Object

Registers an event handler on the instance.

more details
TrackViewModel

Removes a group of handles owned by the object.

more details
Accessor

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

more details
TrackViewModel

Stops tracking the user's location when executed.

more details
TrackViewModel

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.

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 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}

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");
}
on(type, listener){Object}

Registers an event handler on the instance. Call this method to hook an event with a listener.

Parameters

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);
});
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");
start()

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

stop()

Stops tracking the user's location when executed.

Event Overview

Name Type Summary Class
{position: Object}

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

more details
TrackViewModel
{error: Error}

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

more details
TrackViewModel

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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