Valida CNPJ - função em JavaScript

is_cnpj.js

function is_cnpj(c) {
    var b = [6,5,4,3,2,9,8,7,6,5,4,3,2];

    if((c = c.replace(/[^\d]/g,"")).length != 14)
        return false;

    if(/0{14}/.test(c))
        return false;

    for (var i = 0, n = 0; i < 12; n += c[i] * b[++i]);
    if(c[12] != (((n %= 11) < 2) ? 0 : 11 - n))
        return false;

    for (var i = 0, n = 0; i <= 12; n += c[i] * b[i++]);
    if(c[13] != (((n %= 11) < 2) ? 0 : 11 - n))
        return false;

    return true;
};