JSFiddle - React, Tailwind, and code Playground

HTML

<!-- ROGERIO | http://pt.stackoverflow.com/users/25720/rogerio-de-moraes -->
<div id="hora"></div>
<script>
function pad(s) {
    return (s < 10) ? '0' + s : s;
}
/*
function novaHora() {
    function pad(s) {
        return (s < 10) ? '0' + s : s;
    }
    var date = new Date();
    return [date.getHours(), date.getMinutes()].map(pad).join(':');
}

document.write(novaHora());*/

function newData(){
 var date = new Date();
 hora.innerHTML=[date.getHours(), date.getMinutes(),date.getSeconds()].map(pad).join(':');
}

setInterval(function(){
newData();
},500);
</script>
<!-- ROGERIO | http://pt.stackoverflow.com/users/25720/rogerio-de-moraes -->