Track

AMD: require(["esri/widgets/Track"], (Track) => { /* code goes here */ });
ESM: import Track from "@arcgis/core/widgets/Track";
Class: esri/widgets/Track
Inheritance: Track Widget Accessor
Since: ArcGIS API for JavaScript 4.0

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.

For information about gaining full control of widget styles, see the Styling topic.
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 Hide inherited properties
Name 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

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.

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

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

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 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
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
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

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.

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