Tasks Overview

Tasks provide chainable operations for querying and analyzing Esri services, modeled after Esri Leaflet's task pattern.

Pattern

Tasks follow a create → configure → execute pattern. Every configuration method returns the task, so the request only happens when you call an execution method (run(), count(), ids(), …):

const results = await new IdentifyFeatures({ url: '...' })
  .layers([0, 1, 2])
  .tolerance(5)
  .returnGeometry(true)
  .at({ lng: -95, lat: 37 })
  .on(map)
  .run();

.at() does not execute the task

.at() sets the identify geometry and returns the task for chaining. Forgetting the trailing .run() leaves you holding the task object instead of results.

Available Tasks

Task	Description
IdentifyFeatures	Identify features at a point across map services
IdentifyImage	Get pixel values from image services
Query	Spatial and attribute queries with pagination
Find	Text-based search across layers and fields

Task vs Service Methods

Aspect	Task	Service Method
Flexibility	Highly configurable	Basic options
Chaining	Fluent API	Single call
Reusability	Reusable instances	One-time use
Result shape	GeoJSON FeatureCollection (Identify/Query/Find)	Raw ArcGIS response

Authentication

Every task accepts the same auth options as the services — token, apiKey, or an authentication manager — either as constructor options or, for a token, via the chainable .token() method:

new Query({ url: '...', apiKey: 'AAPK…' });
new Find({ url: '...' }).token('eyJ…');

Common Patterns

Reusable Tasks

const queryTask = new Query({ url: '...' })
  .fields(['*'])
  .returnGeometry(true);

const all = await queryTask.where('1=1').run();
const filtered = await queryTask.where('POP > 100000').run();

Error Handling

try {
  const results = await task.run();
} catch (error) {
  console.error('Task failed:', error.message);
}