projections

Wraps proj4 to manage coordinate reference system (CRS) projection definitions. Projections can be registered by name and retrieved or checked later.

listProjections

Signature

listProjections()

Description

Returns the list of all registered projection names, including those built into proj4.

Returns

Type	Description
string[]	Array of projection names

Examples

listProjections()   // ['WGS84', 'EPSG:4326', ...]

registerProjection

Signature

registerProjection(name, def)

Description

Registers a new projection definition under the given name. The definition can be a proj4 string or a configuration object.

Parameters

Name	Type	Required	Description
name	string	yes	Unique projection name (e.g. 'EPSG:2154')
def	string | object	yes	proj4 definition string or configuration object

Throws

Throws if name is not a non-empty string, or if def is neither a non-empty string nor a non-empty object.

Examples

// Register with a proj4 string
registerProjection('EPSG:2154', '+proj=lcc +lat_1=49 +lat_2=44 ...')

// Register with an object
registerProjection('EPSG:2154', { proj: 'lcc', lat1: 49, lat2: 44, ... })

hasProjection

Signature

hasProjection(name)

Description

Returns true if a projection with the given name is registered.

Parameters

Name	Type	Required	Description
name	string	yes	Projection name to look up

Returns

Type	Description
boolean	true if the projection is registered

Throws

Throws if name is not a non-empty string.

Examples

hasProjection('WGS84')      // true
hasProjection('EPSG:2154')  // true — if previously registered
hasProjection('unknown')    // false

getProjection

Signature

getProjection(name)

Description

Returns the proj4 definition object for the given projection name, or undefined if not found.

Parameters

Name	Type	Required	Description
name	string	yes	Projection name to retrieve

Returns

Type	Description
object | undefined	The proj4 definition object, or undefined if not registered

Throws

Throws if name is not a non-empty string.

Examples

getProjection('WGS84')
// { projName: 'longlat', datum: 'WGS84', ... }

getProjection('unknown')
// undefined