IdentifyFeatures

Identify features at a point across multiple map services, with advanced tolerance and filtering options.

Interactive Demo

Click anywhere on the map to identify features. Use the layer checkboxes to control which layers are queryable. The identify mode is enabled by default.

Quick Start

import { IdentifyFeatures } from 'esri-gl';

// Create identify task
const identifyTask = new IdentifyFeatures({
  url: 'https://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer',
});

// Configure and execute
const results = await identifyTask
  .at({ lng: -100, lat: 40 }, map)
  .layers([0, 1, 2])
  .tolerance(5)
  .returnGeometry(true);

Constructor

new IdentifyFeatures(options: IdentifyOptions)

Options

Option	Type	Default	Description
url	string		Required MapService URL
layers	Array<number> | string	'all'	Layers to identify
tolerance	number	3	Search tolerance in pixels
returnGeometry	boolean	false	Include feature geometry
maxAllowableOffset	number		Geometry simplification
geometryPrecision	number		Decimal places for geometry
dynamicLayers	Array<object>		Dynamic layer definitions
mapExtent	object		Current map extent
imageDisplay	object		Map image parameters
returnFieldName	boolean	false	Return field names with values
returnUnformattedValues	boolean	false	Return raw field values
token	string		Authentication token

Chainable Methods

.at(point, map)

Execute identification at a geographic point.

• point: {lng: number, lat: number} or [lng, lat]
• map: MapLibre GL or Mapbox GL map instance

.layers(layers)

Set which layers to identify.

• layers: number[] | string - Layer IDs or 'all'

.tolerance(pixels)

Set search tolerance in pixels.

• pixels: number - Search radius from click point

.returnGeometry(include)

Include feature geometry in results.

• include: boolean - Whether to return geometry

.token(authToken)

Set authentication token.

• authToken: string - ArcGIS authentication token

Usage Examples

Basic Identification

const identifyTask = new IdentifyFeatures({
  url: 'https://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer',
});

map.on('click', async e => {
  const results = await identifyTask.at(e.lngLat, map);
  console.log('Identified features:', results);
});

With Layer Filtering

const identifyTask = new IdentifyFeatures({
  url: 'https://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer',
})
  .layers([0, 1, 2]) // Only identify layers 0, 1, and 2
  .tolerance(10) // 10 pixel tolerance
  .returnGeometry(true);

const results = await identifyTask.at({ lng: -95, lat: 37 }, map);

Advanced Configuration

const identifyTask = new IdentifyFeatures({
  url: 'https://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer',
  returnFieldName: true,
  returnUnformattedValues: true,
})
  .layers('visible') // Only identify visible layers
  .tolerance(5)
  .returnGeometry(true);

// Execute with custom map extent
const results = await identifyTask.at({ lng: -100, lat: 40 }, map, {
  mapExtent: map.getBounds(),
  imageDisplay: {
    width: map.getContainer().offsetWidth,
    height: map.getContainer().offsetHeight,
    dpi: 96,
  },
});

Integration with Services

// Use with DynamicMapService
const service = new DynamicMapService('usa-source', map, {
  url: 'https://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer',
  layers: [0, 1, 2, 3],
});

// Create identify task for same service
const identifyTask = new IdentifyFeatures({
  url: 'https://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer',
})
  .layers([0, 1, 2, 3]) // Match service layers
  .tolerance(5);

map.on('click', async e => {
  // Option 1: Task-based (more flexible)
  const taskResults = await identifyTask.at(e.lngLat, map);

  // Option 2: Service method (simpler)
  const serviceResults = await service.identify(e.lngLat, true);
});

Key Features

• Flexible Layer Targeting - Identify specific layers or all visible layers
• Tolerance Control - Adjust search radius for different use cases
• Geometry Options - Include or exclude feature geometry in results
• Chainable Interface - Fluent API for configuration
• Service Integration - Works with any ArcGIS MapServer
• Advanced Filtering - Support for dynamic layers and complex queries

API Reference

For detailed parameter specifications, see IdentifyFeatures API Reference.