JSFiddle - React, Tailwind, and code Playground

HTML

<div id="TimeLeft"></div>

JavaScript

var $timeLeft = $("#TimeLeft");
var endDateTime = new Date("January 1,2013 00:00:00");
(function() {
    var startDateTime = new Date();
    var s, m, h, d = (endDateTime - startDateTime) / 1000 | 0;
    d /= (s = d % 60 | 0, d -= s, 60);
    d /= (m = d % 60 | 0, d -= m, 60);
    d = (h = d % 24 | 0, d -= h, d / 24 | 0);
    $timeLeft.text(d+'日'+h+'時間'+m+'分'+s+'秒');
    window.setTimeout(arguments.callee, 1000);
})();