JSFiddle - React, Tailwind, and code Playground

HTML

<select id="mail">
    <option value="">select</option>
    <option value="mail">Mail</option>
    <option value="fax">Fax</option>
</select>
<div id="jbox" style="display:none;">
    Name:<input type="text" /><br/>
    Contact No:<input type="text" />
</div>

JavaScript

$('#mail').on('change', function() {
  var getSel = $(this).val();
  if (getSel == 'mail')
    {
        $('#jbox').removeAttr('style');
    } else {
        $('#jbox').css('display','none');
    }
});