cpf.validate.final.js

const mod11 = ( num ) => num % 11 
const NOT = ( x ) => !x
const isEqual = ( a ) => ( b ) => b === a 
const mergeDigits = ( num1, num2 ) => `${num1}${num2}`
const getTwoLastDigits = ( cpf ) => `${cpf[ 9 ]}${cpf[ 10 ]}`
const getCpfNumeral = ( cpf ) => cpf.substr( 0, 9 ).split( '' )

const isRepeatingChars = ( str ) => 
  str.split( ‘’ ).every( ( elem ) => elem === str[ 0 ] )

const toSumOfProducts = ( multiplier ) => ( result, num, i ) => 
  result + ( num * multiplier-- )

const getSumOfProducts = ( list, multiplier ) => 
  list.reduce( toSumOfProducts( multiplier ), 0 )

const getValidationDigit = ( multiplier ) => ( cpf ) =>
  getDigit( mod11( getSumOfProducts( cpf, multiplier ) ) )

const getDigit = ( num ) => 
  ( num > 1 )
    ? 11 - num
    : 0

const isRepeatingNumbersCpf = isRepeatingChars

const isValidCPF = ( cpf ) => {
  const CPF = getCpfNumeral( cpf )
  const firstDigit = getValidationDigit( 10 )( CPF )
  const secondDigit = getValidationDigit( 11 )( CPF.concat( firstDigit ) )
  
  return isEqual( getTwoLastDigits( cpf ) )
                ( mergeDigits( firstDigit, secondDigit ) )
}

const validate = ( CPF ) => NOT( isRepeatingNumbersCpf( CPF ) ) && isValidCPF( CPF )

const CPFS = [ 
  '04998264931', '03506838326','04864713901',
  '03506838321', '22222222222', '00000000000' 
]

CPFS.forEach( ( cpf ) => console.log( `${cpf}: ${validate( cpf )}` ) )