JSFiddle - React, Tailwind, and code Playground

HTML

<table border='1'>
    <tr><td>1</td><td>2</td><td>3</td></tr>
    <tr><td>4</td><td>5</td><td>6</td></tr>
    <tr><td>7</td><td>8</td><td>9</td></tr>
</table>

CSS

td{width:33px;}

JavaScript

$('table').find('td').each(function () {
    $(this).attr('title', $(this).text());
});