JS实现简单倒计时

/*倒计时*/
var downTime =  function (endTime,obj,callback){
    /*基本判断*/
    if(!endTime || typeof endTime !== "string") return false;
    /*基本判断*/
    if(!obj || typeof obj !== "object") return false;
    /*获取日期的毫秒*/
    var endTime = Date.parse(endTime);
    /*定时器*/
    setInterval(function () {
        var nowTime  = +new Date();
        /*2个时间的差 毫秒*/
        var minus =endTime - nowTime;
        /*相差的天数*/
        var day = parseInt(minus/1000/60/60/24);
        /*相差的小时*/
        var hours = parseInt(minus/1000/60/60%24);
        /*相差的分钟*/
        var mintue = parseInt(minus/1000/60%60);
        /*获取相差的秒*/
        var second = parseInt(minus/1000%60);

        obj[0].innerHTML = parseInt(hours/10);
        obj[1].innerHTML = hours%10;
        obj[3].innerHTML = parseInt(mintue/10);
        obj[4].innerHTML = mintue%10;
        obj[6].innerHTML = parseInt(second/10);
        obj[7].innerHTML = second%10;

    },1000);
    callback && callback();
};