JSFiddle - React, Tailwind, and code Playground

HTML

<button>clica aqui...</button>

<h1 id="escondida">Olá!!</h1>

CSS

#escondida {
    opacity: 0;
    transition: opacity 1s;
}
.mostrar {
    opacity: 1 !important;
}

JavaScript

$("button").click(function () {
    var $el = $("#escondida");
    $el.addClass('mostrar');
    setTimeout(function () {
        $el.removeClass('mostrar');
    }, 1000);
});