hash the password

gistfile1.txt

UserSchema.pre(‘save’, { var user = this;
// only hash the password if it has been modified (or is new)
if (!user.isModified('password')) return next();

// generate a salt
bcrypt.genSalt(SALT_WORK_FACTOR, function(err, salt) {
    if (err) return next(err);

    // hash the password along with our new salt
    bcrypt.hash(user.password, salt, function(err, hash) {
        if (err) return next(err);

        // override the cleartext password with the hashed one
        user.password = hash;
        next();
    });

I think there is a typo where you forgot 'function(next)'

The code is corrected in https://gist.github.com/FrancescaK/3832833