JSFiddle - React, Tailwind, and code Playground

HTML

<table><tr><td>1</td><td>2</td><td>3</td><td>4</td></tr> </table>

CSS

td { padding: 0.25em; border: 1px solid #000 }

JavaScript

$('td').click(function(){
    alert($(this).prevAll().length);
});