Class: OsGridRef

OsGridRef(easting, northing)

OS Grid References with methods to parse and convert them to latitude/longitude points.

Constructor

new OsGridRef(easting, northing)

Creates an OsGridRef object.
Parameters:
Name Type Description
easting number Easting in metres from OS Grid false origin.
northing number Northing in metres from OS Grid false origin.
Source:
Example
import OsGridRef from '/js/geodesy/osgridref.js';
  const gridref = new OsGridRef(651409, 313177);

Methods

(static) parse(gridref) → {OsGridRef}

Parses grid reference to OsGridRef object. Accepts standard grid references (eg 'SU 387 148'), with or without whitespace separators, from two-digit references up to 10-digit references (1m × 1m square), or fully numeric comma-separated references in metres (eg '438700,114800').
Parameters:
Name Type Description
gridref string Standard format OS Grid Reference.
Source:
Throws:
Invalid grid reference.
Type
Error
Returns:
Numeric version of grid reference in metres from false origin (SW corner of supplied grid square).
Type
OsGridRef
Example
const grid = OsGridRef.parse('TG 51409 13177'); // grid: { easting: 651409, northing: 313177 }

toLatLon(datumopt) → {LatLon}

Converts ‘this’ Ordnance Survey Grid Reference easting/northing coordinate to latitude/longitude (SW corner of grid square). While OS Grid References are based on OSGB-36, the Ordnance Survey have deprecated the use of OSGB-36 for latitude/longitude coordinates (in favour of WGS-84), hence this function returns WGS-84 by default, with OSGB-36 as an option. See www.ordnancesurvey.co.uk/blog/2014/12/2. Note formulation implemented here due to Thomas, Redfearn, etc is as published by OS, but is inferior to Krüger as used by e.g. Karney 2011.
Parameters:
Name Type Attributes Default Description
datum LatLon.datum <optional>
 WGS84 Datum to convert grid reference into.
Source:
Returns:
Latitude/longitude of supplied grid reference.
Type
LatLon
Example
const gridref = new OsGridRef(651409.903, 313177.270);
  const pWgs84 = gridref.toLatLon();                    // 52°39′28.723″N, 001°42′57.787″E
  // to obtain (historical) OSGB36 lat/lon point:
  const pOsgb = gridref.toLatLon(LatLon.datums.OSGB36); // 52°39′27.253″N, 001°43′04.518″E

toString(digitsopt) → {string}

Converts ‘this’ numeric grid reference to standard OS Grid Reference.
Parameters:
Name Type Attributes Default Description
digits number <optional>
 10 Precision of returned grid reference (10 digits = metres); digits=0 will return grid reference in numeric format.
Source:
Returns:
This grid reference in standard format.
Type
string
Example
const gridref = new OsGridRef(651409, 313177).toString(8); // 'TG 5140 1317'
  const gridref = new OsGridRef(651409, 313177).toString(0); // '651409,313177'