JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//code.jquery.com/jquery-3.3.1.slim.min.js"></script>
<link rel="stylesheet" href="//stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css">
<script src="//cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.0/umd/popper.min.js"></script>
<script src="//stackpath.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<script src="http://new.valeri-tour.com.ua/js/bootstrap-datepicker.min.j"></script>
<input id="date_dep" />

JavaScript

r= new Date('Thu Aug 09 2018 22:25:07 GMT+0300');
k=new Date();
k.setDate(r.getDate() +12);
$('#date_dep').val(k);