Validar CPF

cpf.js

// Author: Ramon Barros <contato@ramon-barros.com>
/* jslint devel: true, unparam: true, indent: 4 */
/* global $,document,window,event,url,introJs,XMLHttpRequest,ActiveXObject,onlyNumbers */
function validarCPF(doc) {
    'use strict';
    var i, cpf = doc.replace(/\D/g, ''), pattern = /^(\d{1})\1{10}$/, sum, mod, digit;

    if (cpf.length !== 11) {
        return false;
    }
    if (pattern.test(cpf)) {
        return false;
    }
    sum = 0;
    for (i = 0; i < 9; i += 1) {
        sum += parseInt(cpf.charAt(i), 10) * (10 - i);
    }
    mod = sum % 11;
    digit = (mod > 1) ? (11 - mod) : 0;
    if (parseInt(cpf.charAt(9), 10) !== digit) {
        return false;
    }
    sum = 0;
    for (i = 0; i < 10; i += 1) {
        sum += parseInt(cpf.charAt(i), 10) * (11 - i);
    }
    mod = sum % 11;
    digit = (mod > 1) ? (11 - mod) : 0;
    if (parseInt(cpf.charAt(10), 10) !== digit) {
        return false;
    }
    return true;
}