JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://getbootstrap.com/2.3.2/assets/css/bootstrap.css">
<div class="progress">
    <div class="bar" id="progress"></div>
</div>

CSS

body {padding: 50px;}

JavaScript

function countdown(callback) {
    var bar = document.getElementById('progress'),
    time = 0, max = 5,
    int = setInterval(function() {
        bar.style.width = Math.floor(100 * time++ / max) + '%';
        if (time - 1 == max) {
            clearInterval(int);
            // 600ms - width animation time
            callback && setTimeout(callback, 600);
        }
    }, 1000);
}

countdown(function() {
    alert('Redirect');
});