async function queryHashes()

in firestore-next/test.solution-geoqueries.js [32:75]

• 29 lines of code
• 5 McCabe index (conditional complexity)

async function queryHashes(done) {
  // [START fs_geo_query_hashes]
  const { collection, query, orderBy, startAt, endAt, getDocs } = require('firebase/firestore');

  // Find cities within 50km of London
  const center = [51.5074, 0.1278];
  const radiusInM = 50 * 1000;

  // Each item in 'bounds' represents a startAt/endAt pair. We have to issue
  // a separate query for each pair. There can be up to 9 pairs of bounds
  // depending on overlap, but in most cases there are 4.
  const bounds = geofire.geohashQueryBounds(center, radiusInM);
  const promises = [];
  for (const b of bounds) {
    const q = query(
      collection(db, 'cities'), 
      orderBy('geohash'), 
      startAt(b[0]), 
      endAt(b[1]));

    promises.push(getDocs(q));
  }

  // Collect all the query results together into a single list
  const snapshots = await Promise.all(promises);

  const matchingDocs = [];
  for (const snap of snapshots) {
    for (const doc of snap.docs) {
      const lat = doc.get('lat');
      const lng = doc.get('lng');

      // We have to filter out a few false positives due to GeoHash
      // accuracy, but most will match
      const distanceInKm = geofire.distanceBetween([lat, lng], center);
      const distanceInM = distanceInKm * 1000;
      if (distanceInM <= radiusInM) {
        matchingDocs.push(doc);
      }
    }
  }
  // [END fs_geo_query_hashes]
  done(matchingDocs);
}