Hashing can be done in one function call.

bcrypt.hash(password, 10, function(err, hashedPassword) {
}

hash(data, salt, cb)
data - [REQUIRED] - the data to be encrypted.
salt - [REQUIRED] - the salt to be used to hash the password. if specified as a number then a salt will be generated and used (see examples).

https://github.com/ncb000gt/node.bcrypt.js/