JSFiddle - React, Tailwind, and code Playground

HTML

<div id="countdown"></div>
<p>This is my page. Yay. For demo purposes I'm starting the countdown at 15 so that you don't have to wait a whole minute.</p>

JavaScript

$(document).ready(function() {
    function doCountdown(time, cb) {
        $("#countdown").text(time);
        if (time === 0)
            cb();
        else
            setTimeout(function() {
                doCountdown(time-1, cb);
            }, 1000);
    }
    
    doCountdown(15, updateEntry);
    
    function updateEntry() {
        alert("This is updateEntry()");
    }
});