JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tbody>
        <tr>
            <td>content 1</td>
            <td>content 2</td>
            <td>content 3</td>
        </tr>
        <tr>
            <td colspan="2">content 4</td>
            <td>content 5</td>
        </tr>
        <tr>
            <td colspan="3">content 6</td>
        </tr>
    </tbody>
</table>

JavaScript

$(document).ready(function () {
    var child;
    $("td").each(function () {
        $(this).removeAttr('colspan');
        child+="<tr>"+$(this)[0].outerHTML+"</tr>";
        
    });
    $('tbody').html(child);
});