Query maxmind geolite2 country ( ISO_3166 ) downloadable db

ip-to-country-code.js

var mmdbreader = require('maxmind-db-reader');

module.exports = Open;

function Open(dbPath) {
  var db;
  var queued = [];
  mmdbreader.open(dbPath, dbReady);
  return query;

  function dbReady(err, handle) {
    if (err) throw err;

    db = handle;
    while (queued.length)
      query.apply(null, queued.shift());
  }

  function query(ip, cb) {
    if (! db)
      return queued.push(Array.prototype.slice.call(arguments));

    db.getGeoData(ip, select);
    function select(err, geodata) {
      cb(err, !err && geodata.country.iso_code);
    }
  }
}

if (require.main === module) {
// Download and extract:
// http://geolite.maxmind.com/download/geoip/database/GeoLite2-Country.mmdb.gz
  var db = Open(require('path').join(__dirname, 'GeoLite2-Country.mmdb'));

  db(process.argv[2] || '193.137.100.231', function(err, countryCode) {
    if (err) throw err;
    console.log(countryCode);
  });
}