Kristian Ekenes & MohanRaj Balumuri

ArcGIS API for JavaScript: Using Arcade with your Apps

Session Goals

Overview of Arcade

Using Arcade in the ArcGIS JS API

Take your apps to the next level

What is Arcade?

• An expression language primarily designed for ArcGIS web maps and web scenes• ArcGIS Pro• Runtime SDKs• JavaScript API• Web apps

• Used to provide extra bit of logic to make a map more dynamic

Arcade Purpose

Arcade is NOT intended to be a Full Programming / Scripting Language• Goal : Lightweight and Simple• Equivalent to a Spreadsheet Cell Calculation

Not a replacement for Python for geoprocessing and Automation

Input ValuesArcade

ExpressionResult Value

Unit Conversion

Why another language?

ArcGIS: Make, Share, Anywhere

ArcGIS: Make, Share, Anywhere - Challenges

Mobile and Native Apps

Browser based Apps

• Size of Executable• Security

• Native Access

• Page Size• Security

• XSS• No Binaries

Traditional Development / Scripting Languages

Arcade Goals

Portable• Write an Expression in Pro, have it run in a Browser, or on a Device

Secure• Ensure that Expressions or Scripting do not compromise Security

Lightweight• Most requirements for Scripts and Expressions are Lightweight. The

language should be small, and fast

Geospatial• Scripts should treat Geospatial as First Class Members

Language Overview

Arcade : Language FeaturesDesigned for Simple Expressions

• Single Line - Implicit Returns • Case Insensitive Language• Dictionary Syntax for Field Access

Has Language Features to Support more Complex Scripts• Type System• Implicit and Explicit Type Casting• Flow Control Statements: IF, FOR• Variable Declaration and Assignments• User Defined Functions

Arcade Scripts run and return a value. They are self contained and cannot alter their environment.

Profiles

Global Variables and Profiles

Popup

LabelingFeature Z

Visualization

Attribute RuleConstrain

Attribute RuleValidation

Attribute RuleCalculation

Field Calculate*

Not implemented in the JS API*Not publicly documented

Exploring Profiles and Functions in the Playground

Arcade and the ArcGIS JS API

ESRI JS APIVersion 3.27

ESRI JS APIVersion 4.10

ESRI JS API : Arcade Expressions

Expression Properties are set as Literal Strings

Arcade Interpreter will Execute valueExpression for every Feature

var renderer = {type: “class-breaks”,valueExpression: "( $feature.TOT_VOTES / $feature.REG_VOTERS ) * 100",valueExpressionTitle: "Voter turnout"classBreakInfos: [ ... ],

};

var labelClass = new LabelClass({labelExpressionInfo: {

expression: "$feature.STATION_NAME"},labelPlacement: "below-right",minScale: 2500000

});nameClass.symbol = new TextSymbol();// set the label class to the feature layerfeatureLayer.labelingInfo = [ labelClass ];

Arcade Expressions can be used For Labeling

Practicalities: Scripts in Script

Scripts within Scripts• Lots of String Escaping.• Embed Script in HTML using MIME type text/plain

<script type="text/plain" id="myScript">Proper($feature.CityName)

</script>...var arcadescript = document.getElementById(“myScript").text;

New FeaturesSince last Dev Summit

FeatureSet Functions

Represents a connection to a set of Features in memory or in a serverLazy, iterable, and chainable

var publicLandFeatures = FeatureSetByName($map, "public lands", ["class"], true); var sensitiveAreas = Filter(publicLandFeatures, "class = 'sensitive'"); Count( Intersects( sensitiveAreas, $feature ) );

Demos

Generate Arcade for your usersTake your apps to the next level

Demos

Generate Arcade for your users

Generate Arcade for your users

Expression sharing

Future

Adding Functions & Profiles

Identifying common operations and use cases

• Let us know what you need!

Finding Arcade Resources

ResourcesFor Arcade Documentation https://developers.arcgis.com/arcade

Playgroundhttps://developers.arcgis.com/arcade/playground/

Using Arcade with JS APIhttps://developers.arcgis.com/javascript/latest/guide/arcade/index.html

Blogs and Postshttps://www.esri.com/arcgis-blog/?s=#&tag=arcade-expressions

Arcade Expression sharing repohttps://github.com/Esri/arcade-expressions/

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