naksha-react-ui/lib/geohash/aggregate-geohash.js

Visualize grid heat map or layer map from elastic search or https://github.com/strandls/naksha

"use strict";

var BASE32 = "0123456789bcdefghjkmnpqrstuvwxyz";

module.exports = function (key, level, bin_size) {
  bin_size = bin_size ? bin_size : 16 / Math.pow(2, 1 - key.length & 1) / Math.pow(4, level);
  var key_except_last = key.slice(0, -1);
  var binned_char_at = ~~(BASE32.indexOf(key.slice(-1)) / bin_size);
  return {
    start: key_except_last + BASE32[bin_size * binned_char_at],
    end: key_except_last + BASE32[bin_size * (binned_char_at + 1) - 1]
  };
};