JSFiddle - React, Tailwind, and code Playground

HTML

<table id="table">
  <thead>
    <tr>
      <th>Lap</th>
      <th>Split 1</th>
      <th>Split 2</th>
      <th>Split 3</th>
      <th>Total Time</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>1</td>
      <td>0:31.110</td>
      <td>0:50.490</td>
      <td>0:32.797</td>
      <td>(total time)</td>
    </tr>
  </tbody>
</table>

CSS

#table {
	margin: 60px auto;
	font-family: "Lucida Sans Unicode", "Lucida Grande", Sans-Serif;
    font-size: 14px;
    width: 600px;
    table-layout: fixed;
    text-align: left;
    border-collapse: collapse;
}

#table th {
    font-size: 15px;
    font-weight: normal;
    background: #b9c9fe;
    border-top: 4px solid #aabcfe;
    border-bottom: 1px solid #fff;
    color: #039;
    padding: 8px;
}

#table td {
    background: #e8edff;
    border-bottom: 1px solid #fff;
    color: #669;
    border-top: 1px solid transparent;
    padding: 8px;

JavaScript

var sp1 = $('#table tr td:nth-child(2)').text()
var sp2 = $('#table tr td:nth-child(3)').text()
var sp3 = $('#table tr td:nth-child(4)').text()
var1 = sp1 + sp2 + sp3
 $('td:nth-child(5)').html(var1);