Arcade is a lightweight expression language designed for creating custom content, visualizations, and labels across the ArcGIS platform. In the 3.19 release of the API, Arcade may be used for creating custom data-driven visualizations and labeling. Field values are treated as global variables in Arcade expressions and may be accessed using the following syntax: $feature.FIELD_NAME
. Arcade comes equipped with its own library of functions that allow users to do simple math calculations and text formatting.
Rather than drive visualizations based on the value of a layer's field, users now can pass an expression to renderers and visual variables. The expression will execute for each feature, generating a symbol based on the returned value. This is convenient when a service doesn't have the exact values you need. To leverage Arcade in renderers, you must pass it as a string to the valueExpression
property of the renderer or visual variable.
The following snippet demonstrates how you can write an Arcade expression showing the share of the vote earned in an election by the winner for each geography in the layer.
// CANDIDATE1 and CANDIDATE2 are field values
var arcade = "var votes = [$feature.CANDIDATE1, $feature.CANDIDATE2];"
// Sum() and Max() are built-in Arcade functions
+ "return ( Max(votes) / Sum(votes) ) * 100;";
renderer.setVisualVariables([{
type: "colorInfo",
valueExpression: arcade, // valueExpression points to the Arcade expression
valueExpressionTitle: "Share of winner's votes",
stops: [ ... ]
}]);
The Create a custom visualization using Arcade sample demonstrates how Arcade can be used in the data visualization context.
LabelingArcade may also be used to label features in a FeatureLayer. This is handled in the expression
property of the labelExpressionInfo object of the LabelClass. As of 3.19, the value
property of labelExpressionInfo
is deprecated and Arcade expressions should be used instead.
The snippet below demonstrates how to label features with only the value of a field in the layer. Remember to use the expression
property of the labelExpressionInfo object; the value
property will not understand the Arcade expression.
// returns the value of a field in the layer
// the value of this field will be the label for each feature
var arcade = "$feature.STATION_NAME";
// set the arcade expression to the `expression` property of labelExpressionInfo
var labelClass = new LabelClass({
labelExpressionInfo: {
expression: arcade
},
labelPlacement: "below-right",
minScale: 2500000
});
nameClass.symbol = new TextSymbol();
// set the label class to the feature layer
featureLayer.setLabelingInfo([ labelClass ]);
Take a look at the Label features using Arcade expressions sample to see examples of various Arcade expressions used in the labeling context.
Arcade is convenient for a number of reasons, including providing the ability to save expressions to layer items and web maps in ArcGIS Online or Portal for ArcGIS. That means expressions can be authored in apps and persisted in webmaps throughout the ArcGIS platform.
Be sure to read the full Arcade documentation for details about its syntax and the Arcade guide page for more examples of its usage within the API.
Version 3.19 adds support for Indonesian (id) and Bosnian (bs) locales. See Localization topic for more information about using different locales.
This release of the JavaScript API includes support for vector tiles in any ArcGIS-supported spatial references. Users can build VectorTileLayer packages in any ArcGIS-supported spatial reference. These packages can then be published to Portal for ArcGIS or ArcGIS Online as vector tile layers. Users then can bring these layers into their web apps.
legendOptions
, valueExpression
, valueExpressionTitle
on class ClassBreaksRenderer
legendOptions
, valueExpression
, valueExpressionTitle
on class UniqueValueRenderer
legendOptions
, valueExpression
, valueExpressionTitle
in each of the visual variables: colorInfo
, sizeInfo
, and opacityInfo
.expression
property of the sizeInfo
visual variable was deprecated in 3.19. If creating a visualization where marker and outline sizes are driven by the map scale, then pass the $view.scale
expression to the valueExpression
property of the object.valueExpression
in rotationInfo
.valueExpression
, sqlExpression
, and sqlWhere
in smartMapping
and FeatureLayerStatistics
functions."description": "{Raster.ServicePixelValue.Raw}% of this area is covered by trees."
and the value is an array, the API no longer adds an extra space.Version 3.19 of the ArcGIS API for JavaScript include:
dgrid1
directory, whereas version 0.3.17 should reference the dgrid
directory.
Please refer to the dgrid 0.4 Migration Guide for additional information on migrating to the newer version.
Use the repository on GitHub for the JS API TypeScript definitions.