자바스크립트 날짜 더하는 함수

자바스크립트 날짜 계산 함수

<script language="JavaScript">
<!--
/**
 param date : Date Objeet
 return string "YYYYMMDD"
 usage : getDateObjToStr(new Date());
*/
function getDateObjToStr(date){
 var str = new Array();

 var _year = date.getFullYear();
 str[str.length] = _year;
 
 var _month = date.getMonth()+1;
 if(_month < 10) _month = "0"+_month;
 str[str.length] = _month;
 
 var _day = date.getDate();
 if(_day < 10) _day = "0"+_day;
 str[str.length] = _day
 var getDateObjToStr = str.join("");

 return getDateObjToStr;
}

/**
 getDateObjToStr 함수 필요
 return Today "YYYYMMDD"
*/
function getToday(){
 var d = new Date();
 var getToday = getDateObjToStr(d);
 return getToday;
}

/**
 데이트 계산 함수
 param date : string "yyyymmdd"
 param period : int
 param period_kind : string "Y","M","D"
 param gt_today : boolean
 usage : calcDate("20080205",30,"D");
*/
function calcDate(date,period, period_kind,gt_today){

 var today = getToday();

 var in_year = date.substr(0,4);
 var in_month = date.substr(4,2);
 var in_day = date.substr(6,2);
 
 var nd = new Date(in_year, in_month-1, in_day);
 if(period_kind == "D"){
  nd.setDate(nd.getDate()+period);
 }
 if(period_kind == "M"){
  nd.setMonth(nd.getMonth()+period);
 }
 if(period_kind == "Y"){
  nd.setFullYear(nd.getFullYear()+period);
 }
 var new_date = new Date(nd);
 var calcDate = getDateObjToStr(new_date);
 if(gt_today){ // 금일보다 큰 날짜 반환한다면
  if(calcDate > today){
   calcDate = today;
  }
 }
 return calcDate;
}
//-->
</script>