validate

All validation functions return a result object with the following shape:

{
  valid: boolean,        // whether the object is valid
  errors: { message: string, path?: string, index?: number }[],
  warnings: { message: string, path?: string, index?: number }[]
}

Errors indicate structural or semantic invalidity. Warnings are non-blocking observations (e.g. high coordinate precision, antimeridian crossing, missing geometry).

Paths use a JSON Pointer-like notation: /coordinates/0, /features/2/geometry, /bbox.

---

validatePosition

Signature

validatePosition(coordinates)

Description

Validates a GeoJSON position. Checks that it is an array of 2 or 3 numbers, that longitude is in [-180, 180] and latitude in [-90, 90]. Emits a warning if longitude or latitude precision exceeds 6 decimal digits.

Parameters

Name	Type	Required	Description
coordinates	number[]	yes	A position array [longitude, latitude] or [longitude, latitude, altitude]

Returns

Type	Description
object	Validation result

Examples

validatePosition([2.3522, 48.8566])
// { valid: true, errors: [], warnings: [] }

validatePosition([200, 48.8566])
// { valid: false, errors: [{ message: 'Invalid coordinates: longitude must be in the range -180 to 180' }], warnings: [] }

validatePosition([2.35221234, 48.8566])
// { valid: true, errors: [], warnings: [{ message: 'longitude precision is high (8 decimals, max recommended: 6)' }] }

---

validateBBox

Signature

validateBBox(bbox)

Description

Validates a GeoJSON bounding box. Accepts 4-value (2D) and 6-value (3D) arrays. Validates both the south-west and north-east corners as positions. Checks that south ≤ north. Emits a warning if west > east (antimeridian crossing).

Parameters

Name	Type	Required	Description
bbox	number[]	yes	A bounding box: [west, south, east, north] or [west, south, minAlt, east, north, maxAlt]

Returns

Type	Description
object	Validation result

Examples

validateBBox([-10, -20, 10, 20])
// { valid: true, errors: [], warnings: [] }

validateBBox([-10, 30, 10, 20])
// { valid: false, errors: [{ message: 'Invalid bbox: south (30) must be <= north (20)' }], warnings: [] }

validateBBox([170, -20, -170, 20])
// { valid: true, errors: [], warnings: [{ message: 'bbox crosses the antimeridian (west: 170 > east: -170)' }] }

---

validateCRS

Signature

validateCRS(crs)

Description

Validates a GeoJSON CRS (Coordinate Reference System) object. Supports two types: name (requires a non-empty properties.name string) and link (requires a non-empty properties.href string).

Parameters

Name	Type	Required	Description
crs	object	yes	A CRS object

Returns

Type	Description
object	Validation result

Examples

validateCRS({ type: 'name', properties: { name: 'urn:ogc:def:crs:OGC:1.3:CRS84' } })
// { valid: true, errors: [], warnings: [] }

validateCRS({ type: 'link', properties: { href: '' } })
// { valid: false, errors: [{ message: 'Invalid crs: linked crs must have a non-empty properties.href string' }], warnings: [] }

validateCRS({ type: 'unknown' })
// { valid: false, errors: [{ message: 'Invalid crs: unknown type: unknown' }], warnings: [] }

---

validateGeometry

Signature

validateGeometry(geometry, path = '')

Description

Validates a GeoJSON geometry object. Dispatches validation based on geometry.type. Validates coordinates recursively for all geometry types. For Polygon and MultiPolygon, checks that rings are closed, validates winding order (outer ring counter-clockwise, holes clockwise), and detects self-intersections. For LineString and MultiLineString, warns on antimeridian crossings. If a bbox is present, it is validated as well.

Parameters

Name	Type	Required	Description
geometry	object	yes	A GeoJSON geometry object
path	string	no	Base path for error and warning reporting (default: '')

Returns

Type	Description
object	Validation result

Examples

validateGeometry({ type: 'Point', coordinates: [2.3522, 48.8566] })
// { valid: true, errors: [], warnings: [] }

validateGeometry({ type: 'LineString', coordinates: [[0, 0], [1, 1]] })
// { valid: true, errors: [], warnings: [] }

validateGeometry({ type: 'Polygon', coordinates: [[[0, 0], [1, 0], [1, 1], [0, 0]]] })
// { valid: false, errors: [{ message: 'Invalid LinearRing: first and last position must be identical', ... }], warnings: [] }

validateGeometry({ type: 'LineString', coordinates: [[170, 0], [-170, 0]] })
// { valid: true, errors: [], warnings: [{ message: 'LineString crosses the antimeridian between positions 0 and 1, consider using MultiLineString', ... }] }

validateGeometry({ type: 'Unknown', coordinates: [] })
// { valid: false, errors: [{ message: 'Invalid geometry type: Unknown' }], warnings: [] }

---

validateGeoJson

Signature

validateGeoJson(geoJson)

Description

Validates any GeoJSON object: a geometry, a Feature, or a FeatureCollection. Dispatches to validateGeometry for plain geometries. For Feature, validates the geometry if present, and emits a warning if geometry is absent. For FeatureCollection, validates each feature recursively. If a crs property is present at the root, it is validated as well.

Parameters

Name	Type	Required	Description
geoJson	object	yes	Any GeoJSON object

Returns

Type	Description
object	Validation result

Throws

Throws if geoJson is not a non-empty object.

Examples

validateGeoJson({ type: 'Point', coordinates: [2.3522, 48.8566] })
// { valid: true, errors: [], warnings: [] }

validateGeoJson({
  type: 'Feature',
  geometry: { type: 'Point', coordinates: [2.3522, 48.8566] },
  properties: {}
})
// { valid: true, errors: [], warnings: [] }

validateGeoJson({ type: 'Feature', geometry: null, properties: {} })
// { valid: true, errors: [], warnings: [{ message: 'Feature has no geometry' }] }

validateGeoJson({
  type: 'FeatureCollection',
  features: [
    { type: 'Feature', geometry: { type: 'Point', coordinates: [200, 48.8566] }, properties: {} }
  ]
})
// {
//   valid: false,
//   errors: [{ message: 'Invalid coordinates: longitude must be in the range -180 to 180', path: '/features/0/geometry/coordinates', index: 0 }],
//   warnings: []
// }

validateGeoJson({
  type: 'FeatureCollection',
  features: [],
  crs: { type: 'name', properties: { name: 'urn:ogc:def:crs:OGC:1.3:CRS84' } }
})
// { valid: false, errors: [{ message: 'Invalid FeatureCollection: features must be a non empty array' }], warnings: [] }