JSFiddle - React, Tailwind, and code Playground

HTML

<div>
test
</div>

<button id="btnToggle" type="button">toggle</button>

CSS

div:before {
    content: '1. ';
}

div.red:before{
    color:red;            
}

JavaScript

console.log($('div').prev()); // this is empty
console.log($('div:before')); // this returns the whole div

$(function(){
    $('#btnToggle').click(function(){
        $('div').toggleClass('red');
    });
});