JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<table id="detailsTable" style="width:300px">
<tr>
  <span class="badge badge-primary" id="totalrows"></span>
  <td>Jill</td>
  <td>Smith</td> 
  <td>50</td>
</tr>
<tr>
  <td>Eve</td>
  <td>Jackson</td> 
  <td>94</td>
</tr>
<tr>
  <td>Eve</td>
  <td>Jackson</td> 
  <td>94</td>
</tr>
</table>

CSS

body{
  margin: 0.5in;
}

JavaScript

var rows = $('#detailsTable tr').length;
$('#totalrows').text(rows);