Formantando CPF e CNPJ

function cpfCnpj(v) {
    //Remove tudo o que não é dígito
    v = v.replace(/\D/g, "")
    if (v.length <= 13) { //CPF
        v = v.replace(/^(\d{3})(\d{3})(\d{3})(\d{2})/, "$1.$2.$3-$4");

    } else { //CNPJ
        v = v.replace(/^(\d{2})(\d{3})(\d{3})(\d{4})(\d{2})/, "$1.$2.$3/$4-$5");
    }
    return v
}