JSFiddle - React, Tailwind, and code Playground

HTML

<table id="sample" border="1">
<tr>
    <td>1</td>
    <td>2</td>
    <td>1</td>
    <td></td>
    <td>1</td>
    <td>3</td>
</tr>
<tr>
    <td></td>
</tr>
</table>

JavaScript

$(document).ready(function() {
    
    var colTotal=0;
 var col=$("#sample tr td");
	$(col).each(function()
		{
				colData=$(this).text();
				colTotal+=isNaN(parseInt(colData)) ? 0: parseInt(colData);
		});
    $('#sample tr:last td').text(isNaN(colTotal) ? 0: colTotal);
									
});