latlon-geohash
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    2.0.0 • Public • Published

    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/latlon-geohash@2.0.0';
     
        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.

    Install

    npm i latlon-geohash

    DownloadsWeekly Downloads

    10,659

    Version

    2.0.0

    License

    MIT

    Unpacked Size

    15.7 kB

    Total Files

    5

    Last publish

    Collaborators

    • chrisveness