【2011.09.01】如何使用javaScript代码获取系统时间和日期？

<script type="text/javascript">
function show(time)
{
var str ,colorhead,colorfoot;
var year=time.getYear();         //获取年份
var month=time.getMonth()+1;     //获取月份
if(month<10) month='0'+month;
var day=time.getDate();          //获取日期
if(day<10) day='0'+day;
var hours=time.getHours();       //获取小时
var minutes=time.getMinutes();   //获取分钟
if(minutes<10) minutes='0'+minutes;
var seconds=time.getSeconds();   //获取秒数
if(seconds<10) seconds='0'+seconds;

var week=time.getDay();         //获取星期
if(week==0) colorhead="<font color=\"#FF0000\">";
if  (week > 0 && week < 6)  colorhead="<font color=\"#FF0000\">";
if  (week==6)  colorhead="<font color=\"#FF0000\">";
if  (week==0)  week="星期日";
if  (week==1)  week="星期一";
if  (week==2)  week="星期二";
if  (week==3)  week="星期三";
if  (week==4)  week="星期四";
if  (week==5)  week="星期五";
if  (week==6)  week="星期六";
colorfoot="</font>"
str = colorhead + year + "-" + month + "-" + day + " " + hours + ":" + minutes + ":" + seconds + "  " + week
+ colorfoot;
return(str);
}
function tick()           //设置每1秒更新一次
{
var today;
today = new Date();
document.getElementById("study").innerHTML =show(today);
window.setTimeout("tick()", 1000);
}
tick();
</script>

<marquee direction="left" scrollamount="6" style="font-size: 16px;">
<font>
<span style="font-size:14px;">
<span style="color:#000;">今天是：</span>
<span id="study"></span>
</span>
</font>
</marquee>