JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
<div id="1" class="box">
      <b>Box 1</b>

      <div id="sub_box_1" class="sub_box">
        <input type="text" name="user_name" placeholder='User Name' />
        <button>ADD</button>
      </div>
      <!--sub_box_1-->
    </div>
    <!--1-->

JavaScript

$(document).ready(function() {
  $('.sub_box').hide();
  $('.box').click(function() {
    $(this).children('.sub_box').show();
  });
});