gistfile1.js

sUser.pre('save', function (next) {
  var self = this
    , now = Date.now()
  this.updatedAt = now
  if (this.isNew) this.createdAt = now
  if (!this.isModified('password')) return next();
  co(function *() {
    self.password = yield self.encryptPassword(self.password)
    next()
  })()
})

sUser.methods.encryptPassword = function *(password) {
  var salt = yield thunkify(bcrypt.genSalt)(10)
  return yield thunkify(bcrypt.hash)(password, salt, null)
}

UserSchema.pre('save', function (next) {
  var user = this;
  user.updatedAt = Date.now();
  if (user.isNew) user.createdAt = Date.now();
  if (!user.isModified('password')) return next();
  user.encryptPassword(user.password, function (error, hash) {
    if (hash) user.password = hash;
    next(error);
  });
});

UserSchema.methods.encryptPassword = function (password, callback) {
  bcrypt.genSalt(10, function (error, salt) {
    bcrypt.hash(password, salt, callback);
  });
};