ExpressionInfo | References | ArcGIS Maps SDK for JavaScript

import ExpressionInfo from "@arcgis/core/layers/support/ExpressionInfo.js";

Inheritance:: ExpressionInfo→Accessor

Since: ArcGIS Maps SDK for JavaScript 4.25

The ExpressionInfo class references an Arcade expression following the specification defined by the Arcade Visualization Profile. Expressions must return a string or a number and may access data values from the feature with the $feature profile variable.

This expression is used for defining an AggregateField for use in a FeatureReductionBinning or a FeatureReductionCluster renderer, popup, or label. It is executed once defined inside a layer's FeatureLayer.featureReduction property.

See also

Example

const expressionInfo = new ExpressionInfo({
  title: "Population per square kilometer",
  returnType: "number",
  expression: "$feature.population / AreaGeodetic($feature, 'square-kilometers')"
});

Constructors

Constructor

Parameters

Parameter	Type	Description	Required
properties	`ExpressionInfoProperties`

See the properties table for a list of all the properties that may be passed into the constructor.

Properties

Any properties can be set, retrieved or listened to. See the Watch for changes topic.

Property	Type	Class
`declaredClass` readonly inherited	`string`	Accessor
`expression`	`string`
`returnType`	`"number" \| "string"`
`title`	`string \| null \| undefined`

declaredClass

readonlyinherited Property

Type: string

Inherited from: Accessor

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

expression

Property

Type: string

An Arcade expression following the specification defined by the Arcade Visualization Profile. Expressions must return a string or a number and may access data values from the feature with the $feature profile variable.

See also

Arcade Visualization Profile

Example

// Calculates the percentage of the population that is Asian
expressionInfo.expression = "($feature.Asian / $feature.TOT_POP) * 100";

returnType

Property

Type: "number" | "string"

Indicates the return type of the Arcade expression.

title

Property

Type: string | null | undefined

The title used to describe the value returned by the expression.

Example

expressionInfo.title = "Percent Asian";

Methods

Method	Signature	Class
`fromJSON` inherited static	`fromJSON(json: any): any`	JSONSupportMixin
`clone` inherited	`clone(): this`	ClonableMixin
`toJSON` inherited	`toJSON(): any`	JSONSupportMixin

fromJSON

inheritedstatic Method

Signature: fromJSON (json: any): any

Inherited from: JSONSupportMixin

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.

Parameters

Parameter	Type	Description	Required
json	`any`	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: any
Returns a new instance of this class.

clone

inherited Method

Signature: clone (): this

Inherited from: ClonableMixin

Creates a deep clone of this object. Any properties that store values by reference will be assigned copies of the referenced values on the cloned instance.

Returns: this
A deep clone of the class instance that invoked this method.

toJSON

inherited Method

Signature: toJSON (): any

Inherited from: JSONSupportMixin

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

Returns: any
The ArcGIS portal JSON representation of an instance of this class.