JSFiddle - React, Tailwind, and code Playground

HTML

<div class="fields" data-required="yes" data-type="radio">

<label class="radio-inline">
<input name="nanashi" class="a" value="X" checked="checked" type="radio">中身X</label>

<label class="radio-inline">
<input name="nanashi" class="a" value="Y" type="radio">中身Y</label>

<label class="radio-inline">
<input name="nanashi" class="a" value="Z" type="radio">中身Z</label>

</div>


<p>▼ここに選択内容を表示させたい</p>
<div id="response"></div>
<p>▲ここに選択内容を表示させたい</p>


<script type="text/javascript">
var input = document.getElementsByClassName("a")[0];
var response = document.getElementById('response');
  
var changeResponse = function() {
  response.textContent = input.value; 
};

input.addEventListener('change', changeResponse);

window.onload = changeResponse;

</script>