JSFiddle - React, Tailwind, and code Playground

HTML

<table id="age-table">
  <tr>
    <td>Ваш возраст:</td>

    <td>
      <label>
        <input type="radio" name="age" value="young" checked> младше 18
      </label>
      <label>
        <input type="radio" name="age" value="mature"> от 18 до 50
      </label>
      <label>
        <input type="radio" name="age" value="senior"> старше 60
      </label>
    </td>
  </tr>

</table>

JavaScript

var parenBlock = document.getElementById("age-table");
 var childBlock = parenBlock.getElementsByTagName("age");
  alert(childBlock[1].innerHTML);