JavaScript to achieve JD.com flash sale effect

* {
            margin: 0;
            padding: 0;
        }
        
        .box {
            width: 190px;
            height: 270px;
            color: #fff;
            text-align: center;
            margin: 100px auto;
            background-color: #d00;
            padding-top: 40px;
            box-sizing: border-box;
        }
        
        .box>h3 {
            font-size: 26px;
        }
        
        .box>p:nth-of-type(1) {
            color: rgba(255, 255, 255, .5);
            margin-top: 5px;
        }
        
        .box>i {
            display: inline-block;
            margin-top: 5px;
            margin-bottom: 5px;
            font-size: 40px;
        }
        
        .box>.time {
            display: flex;
            justify-content: center;
            margin-top: 10px;
        }
        
        .time>div {
            width: 40px;
            height: 40px;
            background: #333;
            line-height: 40px;
            text-align: center;
            font-weight: 700;
            position: relative;
        }
        
        .time>div::before {
            content: "";
            display: block;
            width: 100%;
            height: 2px;
            background: #d00;
            position: absolute;
            left: 0;
            top: 50%;
            transform: translateY(-50%);
        }
        
        .time>.minute {
            margin: 0 10px;
}

<div class="box">
        <h3>Jingdong flash sale</h3>
        <p>FLASH DEALS</p>
        <i class="iconfont icon-lightningbshandian"></i>
        <p>There are still 10 minutes left in this game</p>
        <div class="time">
            <div class="hour">00</div>
            <div class="minute">00</div>
            <div class="second">00</div>
        </div>
 </div> 

//1. Get the element to be operated const oHour = document.querySelector(".hour");
const oMinute = document.querySelector(".minute");
const oSecond = document.querySelector(".second");
 
//2. Processing time difference const remDate = new Date("2021-10-28 23:59:59");
 
        setTime(remDate);
 
        //Start the timer setInterval(function() {
            setTime(remDate);
        }, 1000);
 
        //In order to let users see the effect as soon as they come in, instead of three 00s first
        // We can encapsulate it function setTime(remDate) {
            const obj = getDifferTime(remDate);
            // console.log(obj);
 
            //3. Set the difference to the element oHour.innerText = obj.hour;
            oMinute.innerText = obj.minute;
            oSecond.innerText = obj.second;
        }
 
        function getDifferTime(remDate, curDate = new Date()) {
            //1. Get the difference between two times (milliseconds)
            const differTime = remDate - curDate;
 
            //2. Get the difference between two times (seconds)
            const differSecond = differTime / 1000;
 
            //3. Use the total number of seconds of difference / the number of seconds of each day = the number of days of difference let day = Math.floor(differSecond / (60 * 60 * 24));
            day = day >= 10 ? day : "0" + day;
 
            //4. Use the total number of seconds/hours % 24
            let hour = Math.floor(differSecond / (60 * 60) % 24);
            hour = hour >= 10 ? hour : "0" + hour;
 
            //5. Use the total number of seconds/minutes of difference % 60
            let minute = Math.floor(differSecond / 60 % 60);
            minute = minute >= 10 ? minute : "0" + minute;
 
            // 6. Use the total number of seconds of difference % seconds let second = Math.floor(differSecond % 60);
            second = second >= 10 ? second : "0" + second;
 
            return {
                day: day,
                hour: hour,
                minute: minute,
                second: second,
            }
        }