Even though this plugin has a wide range of validation functions it's designed to require as little network traffic as possible.
error Message Key - Name of language property that is used in case the value of the input is invalid.
error Message - An alternative error message that is used if error Message Key is left with an empty value or isn't defined in the language object.
validator Function - Callback function that validates the input.
Should return a boolean telling if the value is considered valid or not.