Using async/forEachSeries() to collect data from several mongodb collections and then call callback on it

foreachseries_mongodb.js

var async = require('async');
var mongo = require('mongodb');
var Db = mongo.Db,
    Server = mongo.Server,
    Connection = mongo.Connection;
var db = new Db('local', new Server('127.0.0.1', Connection.DEFAULT_PORT, {}));

var collections = ['names', 'fruits'];
var retData = {};

function collectIt(collName, callback) {
    db.collection(collName, function(err, collection) {
        collection.find().toArray(function (err, items) {
            retData[collName] = items;
            callback();
        });
    })
}

db.open(function(err, db) {
    async.forEachSeries(collections, collectIt, function(err) {
        db.close();
        if (err) {
            console.log('sorry.. an error occured');
        } else {
            console.dir('retData:' + JSON.stringify(retData));
        }
    });
});