como-usar.js

var user = require('./userSchema');
user.validate({password: 'alan', email: 'huehue@br.br'}, function(err, data){
  if(err)
    throw err;
    
  //gravar o data no banco de dados
  db.insert(data);
});

userSchema.js

var Joi = require('joi');

var schema = Joi.object().keys({
  attributes: Joi.object(),
  password: Joi.string().regex(/[a-zA-Z0-9]{3,30}/),
  email: Joi.string().email()
}).with('email', 'attributes').without('password');


module.exports = {
  validate: function(data, callback){
    Joi.validate(data, schema, callback);
  }
};