日期加天数怎么加啊？

例如：
将2003-12-15 10:09:54的时间值加上5天变成2003-12-20 10:09:54
该怎么实现呢？
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function DateAdd(strInterval, NumDay, dtDate) {
var dtTmp = new Date(dtDate);
if (isNaN(dtTmp)) dtTmp = new Date();
switch (strInterval) {
case "s":return new Date(Date.parse(dtTmp) + (1000 * NumDay));
case "n":return new Date(Date.parse(dtTmp) + (60000 * NumDay));
case "h":return new Date(Date.parse(dtTmp) + (3600000 * NumDay));
case "d":return new Date(Date.parse(dtTmp) + (86400000 * NumDay));
case "w":return new Date(Date.parse(dtTmp) + ((86400000 * 7) * NumDay));
case "m":return new Date(dtTmp.getFullYear(), (dtTmp.getMonth()) + NumDay, dtTmp.getDate(), dtTmp.getHours(), dtTmp.getMinutes(), dtTmp.getSeconds());
case "y":return new Date((dtTmp.getFullYear() + NumDay), dtTmp.getMonth(), dtTmp.getDate(), dtTmp.getHours(), dtTmp.getMinutes(), dtTmp.getSeconds());
}
}

var d = new Date("2003/12/15 10:09:54")
alert(DateAdd("d",5,d).toLocaleDateString())
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Javascript:

1<script>   
2document.write(new Date(new Date("2003/12/15 10:09:54").getTime()+5*24*60*60*1000).toLocaleString())   
3</script>

VBscript:

1<script language="vbs">   
2document.write "现在起5天以后的时间："   
3document.write DateAdd("d",5,"2003-12-15 10:09:54")   
4</script>

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注意月份

 1<script language="javascript" type="text/javascript">   
 2var originalTime = new Date (2003, (12-1), 15, 10, 09, 54); // 月份从 0-11，tmd外国变态老   
 3var anIntValue = 0;   
 4var caculatedTime = null;   
 5  
 6anIntValue = originalTime.getTime (); // 只能 1970.01.01 之后的日期   
 7anIntValue += 5 * (24 * 3600 * 1000);   
 8caculatedTime = new Date (anIntValue);   
 9alert (caculatedTime);   
10</script>

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用vb比较方便

1<script>   
2document.write DateAdd("d",5,"2003-12-15 10:09:54")   
3</script>

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同意cloudchen(陈系上.net) ( ) 的，很方便
-
不过这里要修改一下
alert(DateAdd("d",5,d).toLocaleString())