JavaScript特效：时间倒数

var Tid;
var SetTime=4*60*60*1000;  //设置毫秒数，1000毫秒为1秒
function LTime(){
    var MyDiv=document.getElementById("mydiv");
    var Time,TempTime,Days,Hours,Minutes,Seconds;
    
    SetTime-=1000;
    if (SetTime<(60*1000)){  //当小于1分钟
        Seconds=Math.floor(SetTime/1000);
        Time=Seconds+"秒";
    }
    else if (SetTime<(60*60*1000)){  //当小于1小时
        Minutes=Math.floor(SetTime/(60*1000));
        
        TempTime=SetTime-(Minutes*60*1000);
        Seconds=Math.floor(TempTime/1000);
        
        Time=Minutes+"分"+Seconds+"秒";
    }
    else if (SetTime<(24*60*60*1000)){  //当小于1天
        Hours=Math.floor(SetTime/(60*60*1000));
        
        TempTime=SetTime-(Hours*60*60*1000)
        Minutes=Math.floor(TempTime/(60*1000));
        
        TempTime=TempTime-(Minutes*60*1000);
        Seconds=Math.floor(TempTime/1000);
        
        Time=Hours+"小时"+Minutes+"分"+Seconds+"秒";
    }
    else if (SetTime>