LabelClass

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

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

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 Working with Properties topic.
Show inherited properties Hide inherited properties
Name Type Summary Class
Boolean

Specifies whether or not a polyline label can overrun the feature being labeled.

more details
LabelClass
String

The name of the class.

more details
Accessor
String

Defines how labels should be placed relative to one another.

more details
LabelClass
String

Defines the labels for a MapImageLayer.

more details
LabelClass
Object

Defines the labels for a FeatureLayer.

more details
LabelClass
String

The position of the label.

more details
LabelClass
String

Specifies the orientation of the label position of a polyline label.

more details
LabelClass
Number

The maximum scale (most zoomed in) at which labels are visible in the view.

more details
LabelClass
Number

The minimum scale (most zoomed out) at which labels are visible in the view.

more details
LabelClass
Boolean

Indicates whether or not to repeat the label along the polyline feature.

more details
LabelClass
Number

The size in points of the distance between labels on a polyline.

more details
LabelClass
TextSymbol|LabelSymbol3D

Defines the symbol used for rendering the label.

more details
LabelClass
Boolean

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

more details
LabelClass
String

A SQL where clause used to determine the features to which the label class should be applied.

more details
LabelClass

Property Details

allowOverrun Boolean
Since: ArcGIS API for JavaScript 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 Stringreadonly inherited
Since: ArcGIS API for JavaScript 4.7

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

deconflictionStrategy String
Since: ArcGIS API for JavaScript 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
layer-deconfliction-on layer-deconfliction-off

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
cluster-deconfliction-on cluster-deconfliction-off

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 String

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 Object

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

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
optional

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

Default Value:null
See also
Example
// For Spokane County, WA, label will display: "Spokane County, Washington"
labelClass.labelExpressionInfo = {
  expression: "$feature.COUNTY_NAME + ' County, ' + $feature.STATE_NAME"
};
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 center-along label placement in 2D MapViews.

Possible Values:"above-center"|"above-left"|"above-right"|"below-center"|"below-left"|"below-right"|"center-center"|"center-left"|"center-right"|"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"|"always-horizontal"

Default Value:null
See also
Example
labelClass.labelPlacement = "above-right";
labelPosition String
Since: ArcGIS API for JavaScript 4.22

Specifies the orientation of the label position of a 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, 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 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 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 Boolean
Since: ArcGIS API for JavaScript 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 Numberautocast
Autocasts from Number|String
Since: ArcGIS API for JavaScript 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
};

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 Boolean

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

where String

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

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
LabelClass

Creates a deep clone of the LabelClass.

more details
LabelClass
*

Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product.

more details
LabelClass
Boolean

Returns true if a named group of handles exist.

more details
Accessor

Removes a group of handles owned by the object.

more details
Accessor
Object

Converts an instance of this class to its ArcGIS portal JSON representation.

more details
LabelClass

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.

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(json){*}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
* Returns a new instance of this class.
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");
}
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");
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.

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