//計(jì)算兩個(gè)時(shí)間之間的時(shí)間差 多少天時(shí)分秒
        function intervalTime(startTime, endTime) {
            var timestamp = Date.parse(new Date()) / 1000; //計(jì)算當(dāng)前時(shí)間戳 (毫秒級(jí))
            var dateBegin = new Date(startTime).getTime();
            var dateEnd = new Date(endTime).getTime();
            var date1 = dateBegin;
            var date2 = dateEnd; //結(jié)束時(shí)間
            var date3 = (date2 - date1) * 1000; //時(shí)間差的毫秒數(shù)
            //計(jì)算出相差天數(shù)
            var days = Math.floor(date3 / (24 * 3600 * 1000 * 1000));
            //計(jì)算出小時(shí)數(shù)
            var leave1 = date3 % (24 * 3600 * 1000 * 1000); //計(jì)算天數(shù)后剩余的毫秒數(shù)
            var hours = Math.floor(leave1 / (60 * 60 * 1000 * 1000));
            //計(jì)算相差分鐘數(shù)
            var leave2 = leave1 % (60 * 60 * 1000 * 1000); //計(jì)算小時(shí)數(shù)后剩余的毫秒數(shù)
            var minutes = Math.floor(leave2 / (60 * 1000 * 1000));
            //計(jì)算相差秒數(shù)
            var leave3 = leave2 % (60 * 1000 * 1000); //計(jì)算分鐘數(shù)后剩余的毫秒數(shù)
            var seconds = Math.round(leave3 / (1000 * 1000));
            console.log(days + "天 " + hours + "小時(shí) ");
            // return   days + "天 " + hours + "小時(shí) " + minutes + " 分鐘" + seconds + " 秒"
            return days + "天 " + hours + "小時(shí) " + minutes + " 分鐘";
        }

        var startTime = "2021-12-20 18:36:29"
        var endTime = "2021-12-20 20:00:00"
        var oldTime1 = (new Date("2021-12-20 18:36:29")).getTime(); //得到毫秒數(shù) 
        var oldTime2 = (new Date("2021-12-20 20:00:00")).getTime(); //得到毫秒數(shù) 

        console.log(intervalTime(oldTime1, oldTime2));

代碼還可以優(yōu)化