Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 | 1x 1485x 1x 1484x 1484x 1484x 1484x 1484x 1484x 7455x 7455x 7455x 1x 7454x 37270x 37270x 19368x 19368x 17902x 17902x 37270x 1483x 1x | /** ****************************************************************************************************
* File: geohashToBBox.js
* Project: geohash
* @author Nick Soggin <iSkore@users.noreply.github.com> on 19-Feb-2019
*******************************************************************************************************/
'use strict';
const
{
BASE32,
MIN_LNG,
MIN_LAT,
MAX_LNG,
MAX_LAT
} = require( './variables' );
/**
* geohashToBBox
* @description
* Returns BBox bounds of specified geohash.
* @param {string} hash - geohash to convert to bbox
* @returns {number[]} bbox array
* @throws Invalid geohash.
*/
function geohashToBBox( hash ) {
if ( hash.length === 0 ) {
throw new Error( 'Invalid geohash' );
}
let
evenBit = true,
lngMin = MIN_LNG,
latMin = MIN_LAT,
lngMax = MAX_LNG,
latMax = MAX_LAT;
for ( let i = 0; i < hash.length; i++ ) {
const
chr = hash.charAt( i ),
hashChar = BASE32.indexOf( chr );
if ( hashChar === -1 ) {
throw new Error( 'Invalid geohash' );
}
for ( let n = 4; n >= 0; n-- ) {
const bitN = hashChar >> n & 1;
if ( evenBit ) {
// longitude
const lngMid = ( lngMin + lngMax ) / 2;
bitN === 1 ? lngMin = lngMid : lngMax = lngMid;
}
else {
// latitude
const latMid = ( latMin + latMax ) / 2;
bitN === 1 ? latMin = latMid : latMax = latMid;
}
evenBit = !evenBit;
}
}
return [ lngMin, latMin, lngMax, latMax ];
}
module.exports = geohashToBBox;
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