JSFiddle - React, Tailwind, and code Playground

HTML

<a href="">1</a>

<a href="">a</a>

<a href="">2</a>

CSS

.sua-classe {
    background:red;
}

JavaScript

$('a').each(function () {
    var t = $(this);
    if (!isNaN(t.html())) {
        t.addClass('sua-classe');
    }
});