NodeJS + mongo-native: access with password

I need to access my mongodb from node with login and pass. Here how I do it now:

var mongo = require('mongodb'),
    Server = mongo.Server,
    Db = mongo.Db,
    ObjectID = require('mongodb').ObjectID;
var BSON = mongo.BSONPure;
var server = new Server('localhost', 27017, {
    auto_reconnect: true
});
var db = new Db('mybase', server);

What should I do to authentificate with password?

Call db.authenticate after opening a connection to the server.

db.open(function(err, db) {
    db.authenticate('username', 'password', function(err, result) {
        ...
    });
  });
});