var inter;

intervatest("2019-08-22 09:12:00");

function intervatest(str) {
    ShowCountDown(str, 'sjtest');
    inter = window.setInterval(function () {
        ShowCountDown(str, 'sjtest');
    }, 1000);
}

clearInterval(inter);

function ShowCountDown(t, divname) {
    var now = new Date();
    var endDate = new Date(t);
    var leftTime = endDate.getTime() - now.getTime();
    var dd = parseInt(leftTime / 1000 / 60 / 60 / 24, 10);//计算剩余的天数
    var hh = parseInt(leftTime / 1000 / 60 / 60 % 24, 10);//计算剩余的小时数
    var mm = parseInt(leftTime / 1000 / 60 % 60, 10);//计算剩余的分钟数
    var ss = parseInt(leftTime / 1000 % 60, 10);//计算剩余的秒数
    dd = checkTime(dd);
    hh = checkTime(hh);
    mm = checkTime(mm);
    ss = checkTime(ss);//小于10的话加0
    var cc = document.getElementById(divname);
    // cc.innerHTML = "距离" + year + "年" + month + "月" + day + "日还有：" + dd + "天" + hh + "小时" + mm + "分" + ss + "秒";
    if (cc != null){
        cc.innerHTML =  dd + ":" + hh + ":" + mm + ":" + ss;
    }
}

function checkTime(i) {
    if (i < 10) {
        i = "0" + i;
    }
    return i;
}