JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
<body>
<div id="timer"></div>
</body>

JavaScript

$(function(){
	timer();
});
function timer(){
    var today = new Date();
    var h = today.getHours();
    var m = today.getMinutes();
    var s = today.getSeconds();
    m = checkTime(m);
    s = checkTime(s);
    $("#timer").text(h + ":" + m + ":" + s);
    var t = setTimeout(timer, 1000);
}

function checkTime(i) {
    if (i < 10){
        i = "0" + i;
    }
    return i;
}