extract

This module provides operators to extract information from GeoJSON objects.

extractGeoJsonNode

Signature

extractGeoJsonNode (geoJson, path)

Description

Extracts the node reachable through a dot-separated path within a GeoJSON object. The path can traverse both object properties and array indexes.

Returns undefined if the path cannot be resolved.

Parameters

Name	Type	Required	Description
geoJson	object	yes	Any valid GeoJSON object
path	string	yes	Dot-separated path to the node

Returns

Type	Description
* | undefined	The node found at path, or undefined if the path cannot be resolved

Throws

Throws if geoJson is not a valid GeoJSON object.

Throws if path is not a non-empty string.

Examples

extractGeoJsonNode({
  type: 'Feature',
  geometry: { type: 'Point', coordinates: [2.349, 48.864] },
  properties: { name: 'Paris' }
}, 'properties.name')
// 'Paris'

extractGeoJsonNode({
  type: 'FeatureCollection',
  features: [
    {
      type: 'Feature',
      geometry: { type: 'Point', coordinates: [2.349, 48.864] },
      properties: { name: 'Paris' }
    }
  ]
}, 'features.0.properties.name')
// 'Paris'

extractGeoJsonNode({
  type: 'Point',
  coordinates: [2.349, 48.864]
}, 'coordinates.1')
// 48.864

extractGeoJsonNode({
  type: 'Feature',
  geometry: null,
  properties: {}
}, 'properties.name')
// undefined

extractGeoJsonBBox

Signature

extractGeoJsonBBox (geoJson)

Description

Extracts the bbox member declared by a GeoJSON object.

The bounding box is returned as stored in the GeoJSON object. No bounding box is computed when the bbox member is absent; in that case, undefined is returned.

Use computeGeoJsonBoundingBox when a bounding box must be computed from the coordinates of a GeoJSON object.

Parameters

Name	Type	Required	Description
geoJson	object	yes	Any valid GeoJSON object

Returns

Type	Description
number[] | undefined	The declared bounding box, or undefined if no bbox member is present

Throws

Throws if geoJson is not a valid GeoJSON object.

Examples

// 2D bbox
extractGeoJsonBBox({
  type: 'Point',
  coordinates: [2.349, 48.864],
  bbox: [2.349, 48.864, 2.349, 48.864]
})
// [2.349, 48.864, 2.349, 48.864]

// 3D bbox
extractGeoJsonBBox({
  type: 'Point',
  coordinates: [2.349, 48.864, 100],
  bbox: [2.349, 48.864, 100, 2.349, 48.864, 100]
})
// [2.349, 48.864, 100, 2.349, 48.864, 100]

// No declared bbox
extractGeoJsonBBox({
  type: 'LineString',
  coordinates: [[2.349, 48.864], [4.835, 45.764]]
})
// undefined

extractGeoJsonCRS

Signature

extractGeoJsonCRS (geoJson)

Description

Extracts and resolves the coordinate reference system (CRS) declared by a GeoJSON object.

When no crs member is declared, WGS84 is returned.

EPSG URN designations such as urn:ogc:def:crs:EPSG::2154 are normalized to their short EPSG:2154 form. Other CRS names are returned as-is.

For complete GeoJSON documents, validateGeoJson and reprojectGeoJson support a single CRS declaration on the root object. Nested CRS declarations are not supported by the validation contract.

Parameters

Name	Type	Required	Description
geoJson	object	yes	Any valid GeoJSON object

Returns

Type	Description
string | undefined	The resolved CRS name, WGS84 if none is declared, or undefined if a declared CRS has no name

Throws

Throws if geoJson is not a valid GeoJSON object.

Examples

// No declared CRS
extractGeoJsonCRS({
  type: 'Point',
  coordinates: [2.349, 48.864]
})
// 'WGS84'

// EPSG designation
extractGeoJsonCRS({
  type: 'Point',
  coordinates: [700000, 6600000],
  crs: {
    type: 'name',
    properties: { name: 'EPSG:2154' }
  }
})
// 'EPSG:2154'

// EPSG URN
extractGeoJsonCRS({
  type: 'Point',
  coordinates: [700000, 6600000],
  crs: {
    type: 'name',
    properties: { name: 'urn:ogc:def:crs:EPSG::2154' }
  }
})
// 'EPSG:2154'

// Other CRS names are preserved
extractGeoJsonCRS({
  type: 'Point',
  coordinates: [2.349, 48.864],
  crs: {
    type: 'name',
    properties: { name: 'urn:ogc:def:crs:OGC:1.3:CRS84' }
  }
})
// 'urn:ogc:def:crs:OGC:1.3:CRS84'