Rounds not optional in bcrypt.genSalt function

[nisargap]

bcrypt.genSalt(function(err, salt){ console.log(salt); });
According to the README the rounds parameter is optional but when I run this it says that no callback was provided.

[vittorio]

Actually, it's not optional parameter
If you don't want to specify count of rounds just call
bcrypt.genSalt(null, callback)