cpf_validation.coffee

validates_cpf = (cpf) ->
    cpf = $.trim(cpf).replace(/\.|\-/g,'').split('')

    # calculate first digit
    sum = 0
    i = 10
    $.each(cpf.slice(0,9), ->
      sum += parseInt(this)*i
      i -= 1
    )

    result = sum % 11
    if result < 2
      result = 0
    else
      result = 11 - result

    if result != parseInt(cpf[9])
      return false


    # calculate second digit
    sum = 0
    i = 11
    $.each(cpf.slice(0,10), ->
      sum += parseInt(this)*i
      i -= 1
    )

    result = sum % 11
    if result < 2
      result = 0
    else
      result = 11 - result

    result == parseInt(cpf[10])