function addDay(dateObj,days){
	var date1 = new Date(dateObj.replace(/[-]/g, "/"));
	date1=date1.valueOf();
	date1=date1+days*1000*60*60*24;
	date1=new Date(date1);
	if(date1.getMonth()+1<=9){
		if(date1.getDate()<=9){
			return date1.getFullYear()+"-0"+(date1.getMonth()+1)+"-0"+date1.getDate();
		}else{
			return date1.getFullYear()+"-0"+(date1.getMonth()+1)+"-"+date1.getDate();
		}
		
	}else{
		if(date1.getDate()<=9){
			return date1.getFullYear()+"-"+(date1.getMonth()+1)+"-0"+date1.getDate();
		}else{
			return date1.getFullYear()+"-"+(date1.getMonth()+1)+"-"+date1.getDate();
		}
	}	
}



//--------------------------------------------------------------------
//作用：日期对象求差
//用法：
//参数：无
//--------------------------------------------------------------------

function dateMinus(dateStr1, dateStr2){
    var date1 = convertDate(dateStr1);
    var date2 = convertDate(dateStr2);
    var daylong = 3600 * 24 * 1000;
    date1 = date1 - date1 %(daylong);
    date2 = date2 - date2 %(daylong);
    var t = date1 - date2;
	var value = (t / (daylong));
    return Math.round(value);  
}

//--------------------------------------------------------------------
//作用：构造日期对象
//用法：
//参数：无
//--------------------------------------------------------------------
function convertDate(dateStr){
    //dateStr的格式最少为“2002-09-12"
    var theYear = dateStr.substring(0, 4);
    //sAlert(theYear);
    var theMonth = dateStr.substring(5, 7);
    //sAlert(theMonth);
    var theDate = dateStr.substring(8, 10);
    //sAlert(theDate);
    var theHour = "";
    var theMinutes = "";
    var theSeconds = "";
    
    if (dateStr.length > 11) //说明有时间参数了
    {
        theHour = dateStr.substring(11, 13);
        theMinutes = dateStr.substring(14, 16);
        theSeconds = dateStr.substring(17, 19);
        
    }
    
    var dateObj = new Date(theYear, theMonth - 1, theDate, theHour, theMinutes, theSeconds);
    return dateObj;
}