geoNear.js

var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var assert = require('assert')

console.log('\n===========');
console.log('    mongoose version: %s', mongoose.version);
console.log('========\n\n');

var dbname = 'testing_so-16747852';
console.log('dbname: %s', dbname);
mongoose.connect('localhost', dbname);
mongoose.connection.on('error', function () {
  console.error('connection error', arguments);
});

var schema = new Schema({
    name: String
  , loc: [Number]
});
schema.index({ loc: '2d' });

var A = mongoose.model('A', schema);
mongoose.connection.on('open', function () {
  var a = new A({ name: 'so-16747852', loc: [8.75913, 40.27239] });

  A.on('index', function (err) {
    if (err) console.log('index error', err);

    a.save(function (err, a) {
      if (err) return done(err);

      // executing the command
      A.db.db.command({
         "geoNear": A.collection.name,
          "uniqueDocs":true,
          "includeLocs":true,
          "near":[
             8.759131,
             40.272393
          ],
          "spherical":false,
          "distanceField":"d",
          "maxDistance":0.09692224622030236,
          "query":{},
          "num":3
      }, {dbName: dbname }, function (err, doc) {
        console.error('found', doc);
        done(err);
      });
    });
  })

});

function done (err) {
  if (err) console.error(err.stack);
  //mongoose.connection.db.dropDatabase(function () {
    mongoose.connection.close();
  //});
}