兼容火狐，IE
代码如下：

<script language="JavaScript" type="text/JavaScript">
var day="";
var month="";
var ampm="";
var ampmhour="";
var myweekday="";
var year="";
mydate=new Date();
myweekday=mydate.getDay();
mymonth=mydate.getMonth()+1;
myday= mydate.getDate();
myyear= mydate.getYear();
year=(myyear > 200) ? myyear : 1900 + myyear;
if(myweekday == 0)
weekday=" 星期日 ";
else if(myweekday == 1)
weekday=" 星期一 ";
else if(myweekday == 2)
weekday=" 星期二 ";
else if(myweekday == 3)
weekday=" 星期三 ";
else if(myweekday == 4)
weekday=" 星期四 ";
else if(myweekday == 5)
weekday=" 星期五 ";
else if(myweekday == 6)
weekday=" 星期六 ";
document.write(year+"年"+mymonth+"月"+myday+"日 "+weekday);
</script>

显示长格式时间。

<script>
document.getElementById('time').innerHTML=new Date().toLocaleString();
setInterval("document.getElementById('time').innerHTML=new Date().toLocaleString()",1000);
</script>