<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<META NAME="Generator" CONTENT="Microsoft FrontPage 4.0">
<META NAME="Author" CONTENT="">
<META NAME="Keywords" CONTENT="">
<META NAME="Description" CONTENT="">
</HEAD><BODY>
有点不准,凑合用吧
<script>
function btnCount_Click(){
var today=new Date("2004/02/29");
var todayDate=today.getDate();
var newDate=new Date(today*1);
var datesum = document.FieldSearchForm.datesum.value;
if(datesum==7) newDate.setDate(newDate.getDate()-7);
else{
if(datesum==30) newDate.setMonth(newDate.getMonth()-1);
else if(datesum==90) newDate.setMonth(newDate.getMonth()-3);
else if(datesum==365) newDate.setFullYear(newDate.getFullYear()-1);
if(todayDate>newDate.getDate()) newDate.setDate(0);//处理不同月份的天数不同而产生的问题
}
alert(today+"\n"+newDate);
}
</script>
<form name="FieldSearchForm"><select size="1" name="datesum">
<option value="7" selected >一周内</option>
<option value="30" >一月内</option>
<option value="90" >三月内</option>
<option value="365" >一年内</option>
</select>
<button onClick="btnCount_Click()">计算N段时间以前的日期</button>
</form>
</BODY>
</HTML>
解决方案 »
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