LabelClass | API Reference | ArcGIS Maps SDK for JavaScript 4.32

Defines label expressions, symbols, scale ranges, label priorities, and label placement options for labels on a layer. See the Labeling guide for more information about labeling.

Known Limitations

Polygon geometries only support always-horizontal labelPlacement.
The available Font properties used in the symbol depends on the layer type, geometry type, and if you are working in 2D or 3D.
Currently, features cannot be properly labeled when a TimeExtent is applied to the layer or view.
Currently, when a FeatureEffect and/or a FeatureFilter is applied to the LayerView, labels may not display properly.
3D SceneViews only support one label per feature. If a feature satisfies the where condition of multiple LabelClasses, then only the label corresponding to the first matching LabelClass is displayed.

See also

Example

const labelClass = {  // autocasts as new LabelClass()
  symbol: {
    type: "text",  // autocasts as new TextSymbol()
    color: "white",
    haloColor: "blue",
    haloSize: 1,
    font: {  // autocast as new Font()
       family: "Ubuntu Mono",
       size: 14,
       weight: "bold"
     }
  },
  labelPlacement: "above-right",
  labelExpressionInfo: {
    expression: "$feature.Team + TextFormatting.NewLine + $feature.Division"
  },
  maxScale: 0,
  minScale: 25000000,
  where: "Conference = 'AFC'"
};

const labelLayer = new FeatureLayer({
  portalItem: {  // autocasts as new PortalItem()
    id: "7f0bfc7bf67a407d8efebf584f6d956d"
  },
  labelingInfo: [labelClass]
});

Constructors

LabelClass Constructor new LabelClass(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 Watch for changes topic.

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Type	Summary	Class
Boolean	Specifies whether or not a polyline label can overrun the feature being labeled.	LabelClass
String	The name of the class.	Accessor
String	Defines how labels should be placed relative to one another.	LabelClass
String\|null\|undefined	Defines the labels for a MapImageLayer.	LabelClass
Object\|null\|undefined	Defines the labels for a FeatureLayer.	LabelClass
String	The position of the label.	LabelClass
String	Specifies the orientation of the label position of a single line polyline label.	LabelClass
Number	The maximum scale (most zoomed in) at which labels are visible in the view.	LabelClass
Number	The minimum scale (most zoomed out) at which labels are visible in the view.	LabelClass
Boolean	Indicates whether or not to repeat the label along the polyline feature.	LabelClass
Number\|null\|undefined	The size in points of the distance between labels on a polyline.	LabelClass
TextSymbol\|LabelSymbol3D	Defines the symbol used for rendering the label.	LabelClass
Boolean	Indicates whether to use domain names if the fields in the labelExpression or labelExpressionInfo have domains.	LabelClass
String\|null\|undefined	A SQL where clause used to determine the features to which the label class should be applied.	LabelClass

Property Details

allowOverrun Property allowOverrun Boolean Since: ArcGIS Maps SDK for JavaScript 4.22 LabelClass since 4.0, allowOverrun added at 4.22.

Specifies whether or not a polyline label can overrun the feature being labeled. For example, after the end of a polyline segment.

Known Limitations

Currently, this property only applies to Polyline FeatureLayer, CSVLayer, and StreamLayer in 2D MapViews.

Default Value:false

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.

deconflictionStrategy Property deconflictionStrategy String Since: ArcGIS Maps SDK for JavaScript 4.16 LabelClass since 4.0, deconflictionStrategy added at 4.16.

Defines how labels should be placed relative to one another. By default, labels have a static deconfliction strategy, meaning labels that overlap are dropped to make them easier to read.

In some cases where few labels overlap, it may be preferable to turn off label deconfliction with the none option. It is also advisable to turn off deconfliction when labeling clusters with a count of features in the center of the cluster.

The following images illustrate when you may, or may not, want labels to deconflict.

When labeling dense layers, the default deconfliction strategy (static) is preferable since labeling all features causes significant overlap, making the labels illegible. Keeping the default setting allows some labels to render. As the user zooms in, all labels will eventually come into view.

static (default)	none

When labeling clusters (or even sparsely distributed features) with small labels, it may be preferable to allow labels to slightly overlap since the information is still legible and doesn't significantly occlude the visualization. In the clustering scenario, a label deconfliction setting of static may actually cause more confusion, making some features not appear to be clusters.

static (default)	none

Known Limitations

Currently, this property only applies to FeatureLayer, CSVLayer, and StreamLayer in 2D MapViews.

Possible Values:"none" |"static"

Default Value:"static"

Example

// Ensures all labels are displayed regardless
// of whether they overlap
labelClass.deconflictionStrategy = "none";

labelExpression Property labelExpression String |null |undefined

Defines the labels for a MapImageLayer. If working with a MapImageLayer that supports Arcade, you can also use labelExpressionInfo instead. To determine this, check the supportsArcadeExpressionForLabeling property. If true, then labelExpression or labelExpressionInfo can be used. If false, then only labelExpression can be used.

If working with FeatureLayer, use labelExpressionInfo instead.

Attribute values may be included in labels using SQL syntax. To include an attribute value in a label, wrap the name of the field in square brackets []. See the example snippet below.

Default Value:null

Example

// For Spokane County, WA, label will display: "Spokane County, Washington"
labelClass.labelExpression = '[COUNTY_NAME] CONCAT " County, " CONCAT [STATE_NAME]';

labelExpressionInfo Property labelExpressionInfo Object |null |undefinedautocast

Defines the labels for a FeatureLayer.

If working with a MapImageLayer that supports Arcade, you can also use labelExpressionInfo. To determine this, check the supportsArcadeExpressionForLabeling property. If true, then labelExpression or labelExpressionInfo can be used. If false, then only labelExpression can be used.

Properties

expression String|null|undefined

An Arcade expression following the specification defined by the Arcade Labeling Profile. Expressions in labels may reference field values using the $feature profile variable and must return a string.

For example, to label a layer of cities with their names, simply reference the field value with the global variable: $feature.CITY_NAME. Expressions can be more sophisticated and use logical functions. This may be useful if you want to use classed labels. For example, the following expression appends city to the end of the label if the feature's population field contains a number greater than 10,000. Otherwise, town is appended to the end of the label. Additionally, you can use TextFormatting.NewLine to add a new line to the label.

IIF($feature.POPULATION > 10000, $feature.NAME + ' city', $feature.NAME + ' town')

title String|null|undefined

The title of the label expression. This is particularly useful in the case of multiple label classes.

Default Value:null

See also

Arcade Labeling Profile

Example

// For Spokane County, WA, label will display: "Spokane County, Washington"
labelClass.labelExpressionInfo = {
  expression: "$feature.COUNTY_NAME + ' County, ' + $feature.STATE_NAME"
};

labelPlacement Property labelPlacement String

The position of the label. Possible values are based on the feature type. This property requires a value.

Feature Type	Possible Values
Points	`above-center`, `above-left`, `above-right`, `below-center`, `below-left`, `below-right`, `center-center`, `center-left`, `center-right`
Polylines	`above-after`, `above-along`, `above-before`, `above-start`, `above-end`, `below-after`, `below-along`, `below-before`, `below-start`, `below-end`, `center-after`, `center-along`, `center-before`, `center-start`, `center-end`
Polygons	`always-horizontal`

Known Limitations

Currently, if the label has a line callout or vertical offset in a 3D SceneView, then only above-center is supported.
Label placement only applies to Point layers in 3D SceneViews.
FeatureLayer Polylines only support above-along, below-along, and center-along label placement in 2D MapViews.

Default Value:null

See also

Example

labelClass.labelPlacement = "above-right";

labelPosition Property labelPosition String Since: ArcGIS Maps SDK for JavaScript 4.22 LabelClass since 4.0, labelPosition added at 4.22.

Specifies the orientation of the label position of a single line polyline label. If "curved", this means the characters follow the curve of the polyline, while "parallel" means the characters will always be straight, and the orientation will be based on the angle of the polyline's curve at the label's position.

Known Limitations

Currently, multiline polyline labels only support the "parallel" property value.
Currently, this property only applies to Polyline FeatureLayer, CSVLayer, and StreamLayer in 2D MapViews.
Currently, this property cannot be saved as part of a WebMap.

Possible Values:"curved" |"parallel"

Default Value:"curved"

maxScale Property maxScale Number

The maximum scale (most zoomed in) at which labels are visible in the view. A value of 0 means the label's visibility does not have a maximum scale. The maxScale value should always be smaller than the minScale value, and greater than or equal to the service specification.

Default Value:0

minScale Property minScale Number

The minimum scale (most zoomed out) at which labels are visible in the view. A value of 0 means the label's visibility does not have a minimum scale. The minScale value should always be larger than the maxScale value, and lesser than or equal to the service specification.

Default Value:0

repeatLabel Property repeatLabel Boolean Since: ArcGIS Maps SDK for JavaScript 4.22 LabelClass since 4.0, repeatLabel added at 4.22.

Indicates whether or not to repeat the label along the polyline feature. If true, the label will be repeated according to the repeatLabelDistance. If false, the label will display once per polyline segment.

Known Limitations

Currently, this property only applies to Polyline FeatureLayer, CSVLayer, and StreamLayer in 2D MapViews.

Default Value:true

repeatLabelDistance Property repeatLabelDistance Number |null |undefinedautocast Autocasts from Number|String Since: ArcGIS Maps SDK for JavaScript 4.22 LabelClass since 4.0, repeatLabelDistance added at 4.22.

The size in points of the distance between labels on a polyline. This value may be autocast with a string expressing size in points or pixels (e.g. 100, or "64pt", or "128px"). The repeatLabel property must be true for this property to be honored.

Known Limitations

Currently, this property only applies to Polyline FeatureLayer, CSVLayer, and StreamLayer in 2D MapViews.

Default Value:null

Example

const labelClass = {  // autocasts as new LabelClass()
  symbol: {
    type: "text",  // autocasts as new TextSymbol()
    color: "white",
    font: {  // autocast as new Font()
       family: "Orbitron",
       size: 12,
       weight: "bold"
     }
  },
  labelExpressionInfo: {
    expression: "$feature.rte_num1"
  },
  labelPlacement: "center-along",
  repeatLabel: true,
  repeatDistanceLabel: 100
};

symbol Property symbol TextSymbol |LabelSymbol3Dautocast

Defines the symbol used for rendering the label. If not set, the default symbol will be used. See the example below.

Example

// If not set, this default symbol will be used
labelClass.symbol = {
  type: "text",
  color: [255, 255, 255, 255],  // white
  font: { family: "Arial Unicode MS", size: 10, weight: "bold" },
  haloColor: [0, 0, 0, 255],  // black
  haloSize: 1
};

useCodedValues Property useCodedValues Boolean

Indicates whether to use domain names if the fields in the labelExpression or labelExpressionInfo have domains.

where Property where String |null |undefined

A SQL where clause used to determine the features to which the label class should be applied. When specified, only features evaluating to true based on this expression will be labeled.

Default Value:null

Examples

labelClass.where = "CITYNAME = 'Redlands'";

labelClass.where = "MARKER_ACTIVITY IN ('Picnicking', 'Group Camping')";

Method Overview

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Return Type	Summary	Class
	Adds one or more handles which are to be tied to the lifecycle of the object.	Accessor
LabelClass	Creates a deep clone of the LabelClass.	LabelClass
*\|null\|undefined	Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product.	LabelClass
Boolean	Returns true if a named group of handles exist.	Accessor
	Removes a group of handles owned by the object.	Accessor
Object	Converts an instance of this class to its ArcGIS portal JSON representation.	LabelClass

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.

clone Method clone(){LabelClass}

Creates a deep clone of the LabelClass.

Returns

Type	Description
LabelClass	A deep clone of the object that invoked this method.

Example

// Creates a deep clone of the layer's first labelClass
let label = layer.labelingInfo[0].clone();

fromJSON Method fromJSON(json){* |null |undefined}static

Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product. The object passed into the input json parameter often comes from a response to a query operation in the REST API or a toJSON() method from another ArcGIS product. See the Using fromJSON() topic in the Guide for details and examples of when and how to use this function.

Parameter

json Object

A JSON representation of the instance in the ArcGIS format. See the ArcGIS REST API documentation for examples of the structure of various input JSON objects.

Returns

Type	Description
* \| null \| undefined	Returns a new instance of this class.

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");
}

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");

toJSON Method toJSON(){Object}

Converts an instance of this class to its ArcGIS portal JSON representation. See the Using fromJSON() guide topic for more information.

Returns

Type	Description
Object	The ArcGIS portal JSON representation of an instance of this class.