JSFiddle - React, Tailwind, and code Playground

HTML

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

CSS

td.Selected {
    color: red;
}

JavaScript

var addEvent = function(event, elem, f) {
    if (elem.attachEvent) {
        elem.attachEvent("on" + event, f);
    } else {
        elem.addEventListener(event, f, false);
    }
};

var addClass = function(elem, className) {
    if (elem.className.indexOf(className) == -1) {
        elem.className += " " + className;
    } else {
        elem.className = elem.className.replace(" " + className, "");    
    }
};

var addSelected = function() {
    addClass(this, "Selected");
};

var tds = document.getElementsByTagName("td");

for (var i = 0, elem = tds[i]; i < tds.length; elem = tds[++i]) {
    addEvent("click", elem, addSelected);
}