nl_tokens: Performs validation for string types .
pl_tokens: function string ( rule , value , callback , source , options ) { const errors = [ ] ; const validate = rule . required || ( ! rule . required && source . hasOwnProperty ( rule . field ) ) ; if ( validate ) { if ( isEmptyValue ( value , 'string' ) && ! rule . required ) { return callback ( ) ; } rules . required ( rule , value , source , errors , options , 'string' ) ; if ( ! isEmptyValue ( value , 'string' ) ) { rules . type ( rule , value , source , errors , options ) ; rules . range ( rule , <mask> , source , errors , options ) ; rules . pattern ( rule , value , source , errors , options ) ; if ( rule . whitespace === true ) { rules . whitespace ( rule , value , source , errors , options ) ; } } } callback ( errors ) ; }