JSFiddle - React, Tailwind, and code Playground

HTML

<table id="t01">
  <tr>
    <th>HEAD 1</th>
    <th>HEAD 2</th>
    <th>HEAD 3</th>
  </tr>
  <tr id="Grp1">
    <td>Grp1 data</td>
    <td>Grp1 data</td>
    <td>Grp1 data</td>
  </tr>
  <tr>
    <td>Grp1 data</td>
    <td>Grp1 data</td>
    <td><textarea></textarea></td>
  </tr>
  <tr>
    <td>Grp1 data</td>
    <td><textarea></textarea></td>
      <td><input type="text" /><input type="text" /></td>
      <td><input type="text" /><input type="text" /></td>
    <td><input type="text"></td>
  </tr>
  <tr id="Grp2">
    <td>Grp2 data</td>
    <td>Grp2 data</td>
    <td>Grp2 data</td>
  </tr>
  <tr>
    <td>Grp2 data</td>
    <td>Grp2 data</td>
    <td><textarea></textarea><input type="text" /></td>
  </tr>
  <tr>
    <td><textarea></textarea></td>
      <td><input type="text" /><input type="text" /></td>
    <td><input type="text" /><input type="text" /></td>
    <td><input type="text" /></td>
  </tr>
  <tr id="Grp3">
    <td>Grp3 data</td>
    <td>Grp3 data</td>
    <td>Grp3 data</td>
  </tr>
  <tr>
    <td>Grp3 data</td>
    <td>Grp3 data</td>
    <td><textarea></textarea><input type="text" /></td>
  </tr>
  <tr>
    <td><textarea></textarea></td>
    <td><input type="text" /><input type="text" /></td>
    <td><input type="text" /><input type="text" /></td>
    <td><input type="text" /></td>
  </tr>
</table>

JavaScript

var curIndex = $("table textarea:eq(1)").closest("tr").index();
var txtlen = $("table tr:eq("+curIndex+")").nextAll('tr').andSelf().find("input[type=text]").length;
alert(txtlen);