JSFiddle - React, Tailwind, and code Playground

HTML

<div id="mensagem" style="display:none"><h1>Isto vai aparecer uma vez por dia! </h1></div>

CSS

#scroller{
    border: .1em solid blue;
    overflow: scroll;
    height: 300px;
}

JavaScript

function setCookie(cname,cvalue,exdays) {
    var d = new Date();
    d.setTime(d.getTime() + (exdays*24*60*60*1000));
    var expires = "expires=" + d.toGMTString();
    document.cookie = cname+"="+cvalue+"; "+expires;
}

function getCookie(cname) {
    var name = cname + "=";
    var ca = document.cookie.split(';');
    for(var i=0; i<ca.length; i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') c = c.substring(1);
        if (c.indexOf(name) == 0) {
            return c.substring(name.length, c.length);
        }
    }
    return "";
}

function showUmaVesPorDia() {
    var user=getCookie("msgCookie");
    if (user != "") {
    } else {
           $("#mensagem").fadeIn('slow');       
           setCookie("msgCookie", 1, 1);
    }
}
$(document).ready(function(){
        showUmaVesPorDia() ;
});