/* 下列函数返回需要的时间 偏移值不能大于30 
 参数：dadd是日偏移值，-表示向前推，+向后推 
     formattype是返回的时间类型 
 返回：返回时间串 
 */  
 function getDiffDate(dadd,formattype)  
 {  
   //可以加上错误处理  
     var a = new Date();  
     a = a.valueOf();  
    a = a + dadd * 24 * 60 * 60 * 1000;  
     a = new Date(a);  
    return formatDate(a,formattype);  
 } 

  //日期自动补零程序  
  function appendZero(n)  
  {  
     return(("00"+ n).substr(("00"+ n).length-2));  
 } 

 function formatDate(day,formattype){  
     var dateString = "";  
     var thisyear = formatYear(day.getFullYear());  
     var thismonth = appendZero(day.getMonth()+1);  
     var thisday  =   appendZero(day.getDate());  
     var thishour = appendZero(day.getHours());  
     var thismin  = appendZero(day.getMinutes());  
     var thissec  = appendZero(day.getSeconds());  
     switch (formattype){  
         case 0:  
             dateString = thisyear + "年" + thismonth + "月" + thisday + "日";  
             break;  
         case 1:  
             dateString = thisyear + "-" + thismonth + "-" + thisday;  
             break;  
         case 2:  
             dateString = thisyear + "-" + thismonth + "-" + thisday+ " " + appendZero(thishour) + ":" + appendZero(thismin) + ":" + appendZero(thissec);  
             break; 
         case 3: 
         	dateString = thismonth + "月" + thisday + "日";  
         	break;
         case 4: 
         	dateString = thisyear + thismonth  + thisday;  
         	break;
         default:  
              dateString = thisyear + "-" + thismonth + "-" + thisday;  
      }  
      return dateString;  
 } 
 
 //把年份格式化成4位   
function formatYear(theYear){    
var tmpYear = parseInt(theYear,10);   
if (tmpYear < 100){   
tmpYear += 1900;   
if (tmpYear < 1940){   
tmpYear += 100;   
}   
}   
if (tmpYear < this.MinYear){   
tmpYear = this.MinYear;   
}   
if (tmpYear > this.MaxYear){   
tmpYear = this.MaxYear;   
 }   
 return(tmpYear);   
  }