javascript实现在某个时间里返回星期和月的第一天和最后一天

     最近在做项目时遇到要统计一个月内的计费，虽用服务器端代码实现了，但用客户端的脚本应更快些
    
     比如在页面上放有如下图的控件时即可用脚本实现更好：
        

                                       
<script language="javascript">
  function fillstring(str)
  {
   if(str.length==1)
   {
    str = "0" + str;
   }
   return(str);
  }
  function quickseldate(type)
  {
   var begintime,endtime;
   var oneminute = 60*1000;
   var onehour   = 60*oneminute;
   var oneday    = 24*onehour;
   var oneweek   = 7*oneday;
   
   var todayDate = new Date();
   var date = todayDate.getDate();
   var month= todayDate.getMonth() +1;
   var year= todayDate.getYear();
   var day = todayDate.getDay();
   if(navigator.appName == "Netscape")
   {
    year = 1900 + year;
   }

   //-->
      
   if(type=="day")
   {
    begintime = year.toString() + "-" + fillstring(month.toString()) + "-" + fillstring(date.toString());
    endtime = begintime;
   }
   else if(type=="week")
   {
    var daytoMon = day-1;
    if(day==0)
     daytoMon = 6;
    
    todayDate.setTime(todayDate.getTime()-daytoMon*oneday);
    date = todayDate.getDate();
    month= todayDate.getMonth() +1;
    year= todayDate.getYear();
    day = todayDate.getDay();
    
    begintime = year.toString() + "-" + fillstring(month.toString()) + "-" + fillstring(date.toString());
    
    todayDate.setTime(todayDate.getTime()+6*oneday);
    
    date = todayDate.getDate();
    month= todayDate.getMonth() +1;
    year= todayDate.getYear();
    
    endtime = year.toString() + "-" + fillstring(month.toString()) + "-" + fillstring(date.toString());
   }
   else if(type=="month")
   {
    var dateto1 = date-1;
    
    todayDate.setTime(todayDate.getTime()-dateto1*oneday);
    date = todayDate.getDate();
    month= todayDate.getMonth() +1;
    year= todayDate.getYear();
    day = todayDate.getDay();
    
    begintime = year.toString() + "-" + fillstring(month.toString()) + "-" + fillstring(date.toString());
    
    todayDate.setMonth(month);
    todayDate.setTime(todayDate.getTime()-oneday);
    
    date = todayDate.getDate();
    month= todayDate.getMonth() +1;
    year= todayDate.getYear();
    
    endtime = year.toString() + "-" + fillstring(month.toString()) + "-" + fillstring(date.toString());

   }

   document.getElementById("Begintime").value = begintime;
   document.getElementById("Endtime").value = endtime;
  }
</script>