latlon-geohash
v2.0.0
Published
Gustavo Niemeyer’s geocoding system
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geohash
Functions to convert a geohash to/from a latitude/longitude point, and to determine bounds of a geohash cell and find neighbours of a geohash.
Note this version 2 uses ES classes and modules: for older browsers (or Node.js <8.0.0), v1.1.0 is ES5-based.
API
Geohash.encode(lat, lon, [precision]): encode latitude/longitude point to geohash of given precision (number of characters in resulting geohash); if precision is not specified, it is inferred from precision of latitude/longitude values.Geohash.decode(geohash): return { lat, lon } of centre of given geohash, to appropriate precision.Geohash.bounds(geohash): return { sw, ne } bounds of given geohash.Geohash.adjacent(geohash, direction): return adjacent cell to given geohash in specified direction (N/S/E/W).Geohash.neighbours(geohash): return all 8 adjacent cells (n/ne/e/se/s/sw/w/nw) to given geohash.
Note to obtain neighbours as an array, you can use
const neighboursObj = Geohash.neighbours(geohash);
const neighboursArr = Object.keys(neighboursObj).map(n => neighboursObj[n]);The parent of a geocode is simply geocode.slice(0, -1).
If you want the geohash converted from Base32 to Base4, you can e.g.:
parseInt(Geohash.encode(52.20, 0.12, 6), 32).toString(4);Usage in browser
Geohash can be used in the browser by taking a local copy, or loading it from jsDelivr: for example,
<!doctype html><title>geohash example</title><meta charset="utf-8">
<script type="module">
import Geohash from 'https://cdn.jsdelivr.net/npm/[email protected]';
const geohash = Geohash.encode(52.20, 0.12, 6);
console.assert(geohash == 'u120fw');
const latlon = Geohash.decode('u120fw');
console.assert(JSON.stringify(latlon) == '{"lat":52.1988,"lon":0.115}');
</script>Usage in Node.js
Geohash can be used in a Node.js app from npm (currently the esm package is required to load ES-modules):
$ npm install latlon-geohash esm
$ node -r esm
> import Geohash from 'latlon-geohash';
> const geohash = Geohash.encode(52.20, 0.12, 6);
> console.assert(geohash == 'u120fw');
> const latlon = Geohash.decode('u120fw');
> console.assert(JSON.stringify(latlon) == '{"lat":52.1988,"lon":0.115}');Further details
More information (with interactive conversion) at www.movable-type.co.uk/scripts/geohash.html.
Full JsDoc at www.movable-type.co.uk/scripts/js/latlon-geohash/docs/Geohash.html.