Demonstração do maskbrdoc
HTML
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script>
<script src="https://rawgit.com/masimao/maskbrdoc/master/maskbrdoc.js"></script>
CPF/CNPJ: <input type="text" class="documento" maxlength="18" />
JavaScript
$('.documento').maskbrdoc();