ScaleBar

AMD: require(["esri/widgets/ScaleBar"], (ScaleBar) => { /* code goes here */ });
ESM: import ScaleBar from "@arcgis/core/widgets/ScaleBar.js";
Class: esri/widgets/ScaleBar
Inheritance: ScaleBar→Widget→Accessor
Since: ArcGIS Maps SDK for JavaScript 4.3

The ScaleBar widget displays a scale bar on the map or in a specified HTML node. The widget respects various coordinate systems and displays units in metric or imperial values. Metric values show either kilometers, meters, centimeters, or millimeters depending on the scale, and likewise, imperial values show miles, feet, or inches depending on the scale. When working with Web Mercator or geographic coordinate systems the scale bar takes into account projection distortion and dynamically adjusts the scale bar. The ScaleBar widget sample, which uses a map that has the Web Mercator projection, shows this behavior. Open the sample and note that as you pan the map south towards the equator the scale bar gets shorter and as you pan north it gets longer.

When the scale bar is inside the map, the actual location of the scale bar is used to calculate the scale. Otherwise, the center of the map is used to calculate the scale.

Known Limitations

ScaleBar only works with MapView.

For information about gaining full control of widget styles, see the Styling topic.
See also
Example
let scaleBar = new ScaleBar({
  view: view
});
// Add widget to the bottom left corner of the view
view.ui.add(scaleBar, {
  position: "bottom-left"
});

Constructors

ScaleBar

Constructor
new ScaleBar(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 scalebar = new ScaleBar({
  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

The ID or node representing the DOM element containing the widget.

Widget

The name of the class.

Accessor

Icon displayed in the widget's button.

ScaleBar

The unique ID assigned to the widget when the widget is created.

Widget

The widget's default label.

ScaleBar

The style for the scale bar.

ScaleBar

Units to use for the scale bar.

ScaleBar

A reference to the MapView.

ScaleBar

The view model for this widget.

ScaleBar

Indicates whether the widget is visible.

Widget

Property Details

container

Inherited
Property
container String |HTMLElement
Inherited from Widget

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 case 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

Inherited
Property
declaredClass Stringreadonly
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.7 Accessor since 4.0, declaredClass added at 4.7.

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

icon

Property
icon String
Since: ArcGIS Maps SDK for JavaScript 4.27 ScaleBar since 4.3, icon added at 4.27.

Icon displayed in the widget's button.

Default Value:"actual-size"
See also

id

Inherited
Property
id String
Inherited from Widget

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

Property
label String

The widget's default label.

style

Property
style String

The style for the scale bar. When unit is set to dual, the style will always be line.

Possible Values:"ruler" |"line"

Default Value:"line"

unit

Property
unit String

Units to use for the scale bar. When using dual, the scale bar displays both metric and imperial units. When metric, distances will be shown in either kilometers, meters, centimeters, or millimeters depending on the scale. Similarly, imperial units will be shown in either miles, feet, or inches.

Possible Values:"metric" |"imperial" |"dual"

view

Property
view MapView

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

viewModel

Property
viewModel ScaleBarViewModelautocast

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

visible

Inherited
Property
visible Boolean
Inherited from Widget

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.

Accessor

A utility method used for building the value for a widget's class property.

Widget

Destroys the widget instance.

Widget

Emits an event on the instance.

Widget

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

Widget

Returns true if a named group of handles exist.

Accessor

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected).

Widget

isRejected() may be used to verify if creating an instance of the class is rejected.

Widget

isResolved() may be used to verify if creating an instance of the class is resolved.

Widget

Registers an event handler on the instance.

Widget

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

Widget

Executes after widget is ready for rendering.

Widget

Removes a group of handles owned by the object.

Accessor

This method is implemented by subclasses for rendering.

Widget

Renders widget to the DOM immediately.

Widget

Schedules widget rendering.

Widget
Promise

when() may be leveraged once an instance of the class is created.

Widget

Method Details

addHandles

Inherited
Method
addHandles(handleOrHandles, groupKey)
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, addHandles added at 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 }
);

this.addHandles(handle);

// Destroy the object
this.destroy();
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

Inherited
Method
classes(classNames){String}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.7 Widget since 4.2, classes added at 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.
Example
// .tsx syntax showing how to set css classes while rendering the widget

render() {
  const dynamicClasses = {
    [css.flip]: this.flip,
    [css.primary]: this.primary
  };

  return (
    <div class={classes(css.root, css.mixin, dynamicClasses)} />
  );
}

destroy

Inherited
Method
destroy()
Inherited from Widget

Destroys the widget instance.

emit

Inherited
Method
emit(type, event){Boolean}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.5 Widget since 4.2, emit added at 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

Inherited
Method
hasEventListener(type){Boolean}
Inherited from Widget

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

Inherited
Method
hasHandles(groupKey){Boolean}
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, hasHandles added at 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

Inherited
Method
isFulfilled(){Boolean}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.19 Widget since 4.2, isFulfilled added at 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

Inherited
Method
isRejected(){Boolean}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.19 Widget since 4.2, isRejected added at 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

Inherited
Method
isResolved(){Boolean}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.19 Widget since 4.2, isResolved added at 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

Inherited
Method
on(type, listener){Object}
Inherited from Widget

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

Inherited
Method
own(handleOrHandles)
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.24 Widget since 4.2, own added at 4.24.
Deprecated since 4.28 Use addHandles() instead.

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
Method
postInitialize()
Inherited from Widget

Executes after widget is ready for rendering.

removeHandles

Inherited
Method
removeHandles(groupKey)
Inherited from Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, removeHandles added at 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

Inherited
Method
render(){Object}
Inherited from Widget

This method is implemented by subclasses for rendering.

Returns
Type Description
Object The rendered virtual node.

renderNow

Inherited
Method
renderNow()
Inherited from Widget

Renders widget to the DOM immediately.

scheduleRender

Inherited
Method
scheduleRender()
Inherited from Widget

Schedules widget rendering. This method is useful for changes affecting the UI.

when

Inherited
Method
when(callback, errback){Promise}
Inherited from Widget
Since: ArcGIS Maps SDK for JavaScript 4.19 Widget since 4.2, when added at 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
});

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