JSFiddle - React, Tailwind, and code Playground

HTML

<select name="contactinfo" id="contactinfo" onchange="CheckContact(this.value);">
  <option>Select Contact Option</option>
  <option value="email" class="email">Email</option>
  <option value="sms"class="email">Text (SMS)</option>
</select><br />
<select>
<option> - </option>
<option id="email" style="display: none;">Enter Email: </option>
<option id="sms" style="display: none;">Enter Cell Number: </option>
</select>

JavaScript

function CheckContact(val){
 var element=document.getElementById('email');
 if(val=='email')
   element.style.display='block';
 else
   element.style.display='none';

 var element=document.getElementById('sms');
 if(val=='sms')
   element.style.display='block';
 else
   element.style.display='none';
}