function startTime()   
{   
 var weekday = new Array(7)     
  weekday[0] = "星期日"   
  weekday[1] = "星期一"   
  weekday[2] = "星期二"   
  weekday[3] = "星期三"   
  weekday[4] = "星期四"   
  weekday[5] = "星期五"   
  weekday[6] = "星期六"   
  
var today=new Date()   
var year=today.getYear()   
var month=today.getMonth()+1   
var day=today.getDate()   
var week= weekday[today.getDay()]   
var h=today.getHours()   
  
var m=today.getMinutes()   
var s=today.getSeconds()   
// add a zero in front of numbers<10  
/*另一种写法   
monthmonth = month<10?"0"+month:month;//如果小于10即显示为09月           
dayday = day<10?"0"+day:day;//如果小于10即显示为09日     
……   
*/   
month=checkTime(month)   
day=checkTime(day)   
h=checkTime(h)   
m=checkTime(m)   
s=checkTime(s)   
document.getElementById('txt').innerHTML=year+"年"+month+"月"+day+"日 "+week+" "+h+":"+m+":"+s   
t=setTimeout('startTime()',500)   
}   
  
function checkTime(i)   
{   
if (i<10)    
  {i="0" + i}   
  return i   
}