时间倒计时

// 格式化时间 2019-1-1 00:00:00
function timeFormat(nowTime) {
    var thisTime = nowTime.replace(/-/g, '/');
    var time = new Date(thisTime).getTime();
    return time;
}
// 小于10前面加0
function checktime(i) {
    if (i < 10) {
        i = "0" + i;
    } else {
        i = i;
    }
    return i;
}
// 开始时间
var start_time = 1554364098000;
// 结束时间
var end_time = 1554364103000;
freshTime(start_time, end_time);
function freshTime() {
    var lefttime = end_time - start_time;
    var dm = 24 * 60 * 60 * 1000;
    var d = parseInt(lefttime / dm);
    var hm = 60 * 60 * 1000;
    var h = parseInt((lefttime / hm) % 24);
    var mm = 60 * 1000;
    var m = parseInt((lefttime / mm) % 60);
    var s = parseInt((lefttime / 1000) % 60);
    m = checktime(m);
    s = checktime(s);
      var now_time = d + "天" + h + "小时" + m + "分钟" + s + "秒";
      console.log(now_time);
    end_time -= 1000;
    if ((end_time - ad_time) < 0) {
        window.clearTimeout(st);
          console.log("倒计时结束");
    } else {
        var st = setTimeout(function() {
            freshTime(ad_time, end_time);
        }, 1000)
    }
}