JSFiddle - React, Tailwind, and code Playground

HTML

<div class="J_countdown2" data-diff="5766998"></div>

JavaScript

(function ($) {
    $.fn.countdown = function (options) {
        // default options
        var defaults = {
            attrName: 'data-diff',
            tmpl: '<span class="hour">%{h}</span><span class="minute">%{m}</span>minutes<span class="second">%{s}</span>seconds',
            end: 'has ended',
            afterEnd: null
        };
        options = $.extend(defaults, options);


        // trim zero
        function trimZero(str) {
            return parseInt(str.replace(/^0/g, ''));
        }
        // convert string to time
        function getDiffTime(str) {
            var m;
            if ((m = /^(\d{4})[^\d]+(\d{1,2})[^\d]+(\d{1,2})\s+(\d{2})[^\d]+(\d{1,2})[^\d]+(\d{1,2})$/.exec(str))) {
                var year = trimZero(m[1]),
                    month = trimZero(m[2]) - 1,
                    day = trimZero(m[3]),
                    hour = trimZero(m[4]),
                    minute = trimZero(m[5]),
                    second = trimZero(m[6]);
                return Math.floor((new Date(year, month, day, hour, minute, second).getTime() - new Date().getTime()) / 1000);
            }
            return parseInt(str);
        }
        // format time
        function format(diff) {
            var tmpl = options.tmpl,
                day, hour, minute, second;
            day = /%\{d\}/.test(tmpl) ? Math.floor(diff / 86400) : 0;

            hour = Math.floor((diff - day * 86400) / 3600);
            minute = Math.floor((diff - day * 86400 - hour * 3600) / 60);

            second = diff - day * 86400 - hour * 3600 - minute * 60;

            if (day < 10) day = "0" + day;
            if (hour < 10) hour = "0" + hour;
            if (minute < 10) minute = "0" + minute;
            if (second < 10) second = "0" + second;
            console.log(second)
            tmpl = tmpl.replace(/%\{d\}/ig, day)
                .replace(/%\{h\}/ig, hour)
                .replace(/%\{m\}/ig, minute)
                .replace(/%\{s\}/ig, second);
           ...