JS日期加减,日期运算代码

function (dd,dadd){
//可以加上错误处理
var a = new Date(dd)
a = a.valueOf()
a = a - dadd  24  60  60  1000
a = new Date(a)
alert(a.getFullYear() + "年" + (a.getMonth() + 1) + "月" + a.getDate() + "日")
}
("12/23/2002",2)

function DateDiff(d1,d2){
  var day = 24  60  60 1000;
try{  
    var dateArr = d1.split("-");
  var checkDate = new Date();
    checkDate.setFullYear(dateArr[0], dateArr[1]-1, dateArr[2]);
  var checkTime = checkDate.getTime();
 
  var dateArr2 = d2.split("-");
  var checkDate2 = new Date();
    checkDate2.setFullYear(dateArr2[0], dateArr2[1]-1, dateArr2[2]);
  var checkTime2 = checkDate2.getTime();
  
  var cha = (checkTime - checkTime2)/day; 
    return cha;
  }catch(e){
  return false;
}
}//end fun

<script language="javascript" type="text/javascript">
var flag = Array();//全局变量

var start = "2009-01-01";
var end = "2009-02-24";
SetFlag(start,end); 

for(var i=0; i<flag.length; i++){
  document.write(flag[i]+"\n\r");
}

//设置周期内的日期(数组)
function SetFlag(start,end){
var cdate = Array();
cdate = start.split("-");
var cd = cdate[1]+"/"+cdate[2]+"/"+cdate[0]; 
var dayNum = DateDiff(end,start);
for(var i=0; i<=dayNum; i++){
  flag.push(AddDays(cd,i));
}
}//end fun
//日期加上天数后的新日期.
function AddDays(date,days){
var nd = new Date(date);
  nd = nd.valueOf();
  nd = nd + days  24  60  60  1000;
  nd = new Date(nd);
  //alert(nd.getFullYear() + "年" + (nd.getMonth() + 1) + "月" + nd.getDate() + "日");
var y = nd.getFullYear();
var m = nd.getMonth()+1;
var d = nd.getDate();
if(m <= 9) m = "0"+m;
if(d <= 9) d = "0"+d; 
var cdate = y+"-"+m+"-"+d;
return cdate;
}
//两个日期的差值(d1 - d2).
function DateDiff(d1,d2){
  var day = 24  60  60 1000;
try{  
    var dateArr = d1.split("-");
  var checkDate = new Date();
    checkDate.setFullYear(dateArr[0], dateArr[1]-1, dateArr[2]);
  var checkTime = checkDate.getTime();
 
  var dateArr2 = d2.split("-");
  var checkDate2 = new Date();
    checkDate2.setFullYear(dateArr2[0], dateArr2[1]-1, dateArr2[2]);
  var checkTime2 = checkDate2.getTime();
  
  var cha = (checkTime - checkTime2)/day; 
    return cha;
  }catch(e){
  return false;
}
}//end fun
</script>