Radio 控制日期文本框

<html>
<head>
<script>
    ChangeDate = function(param) {
      
        var a = document.getElementById('beginTime').value;
  var NowDate= new Date(Date.parse(a.replace(/\-/g,"/")));
        NowDate.setDate(NowDate.getDate()+param);
        document.getElementById('endTime').value=NowDate.toLocaleDateString().replace("年","-").replace("月","-").replace("日","").substr(0, 10);
    };

 

//js截取字符串
function SubstrDemo(){
   var s, ss;                // 声明变量。
   var s = "2011-11-27 星期日";
   ss = s.substr(0, 10); // 获取子字符串。
   alert(ss);               // 返回 "Spain"。
}

  

 function check_radio(){
     var chkObjs = document.getElementsByName("rdOperatingMethods");
       var a = document.getElementById('beginTime').value;
  var NowDate= new Date(Date.parse(a.replace(/\-/g,"/")));
    
               
                    if(chkObjs[0].checked){
                     var a = document.getElementById('beginTime').value;
                        NowDate.setDate(NowDate.getDate()+0);
                      document.getElementById('endTime').value=NowDate.toLocaleDateString().replace("年","-").replace("月","-").replace("日","").substr(0, 10);   
                        }
                       else    if(chkObjs[1].checked){
                     var a = document.getElementById('beginTime').value;
                        NowDate.setDate(NowDate.getDate()+2);
                      document.getElementById('endTime').value=NowDate.toLocaleDateString().replace("年","-").replace("月","-").replace("日","").substr(0, 10);   
                        }
                        if(chkObjs[2].checked){
                     var a = document.getElementById('beginTime').value;
                        NowDate.setDate(NowDate.getDate()+6);
                      document.getElementById('endTime').value=NowDate.toLocaleDateString().replace("年","-").replace("月","-").replace("日","").substr(0, 10);   
                        }
                       
                    }
            
          

 

</script>

</head>
<body>
<input type="button" value="测试" onclick="SubstrDemo();"/>

<form id="fm1">
<table>
<tr>
<td>
 <input id="rdOperatingMethods1" name="rdOperatingMethods" type="radio" value="0"
                   checked="checked" text="今日特价" onclick='ChangeDate(0)' />今日特价
</td>
  
<td> <input id="rdOperatingMethods2" name="rdOperatingMethods" type="radio" value="0"
                   checked="checked" text="3日特价"  onclick='ChangeDate(2)'/>3日特价
</td> 

   <td> <input id="rdOperatingMethods3" name="rdOperatingMethods" type="radio" value="0"
                   checked="checked" text="7日特价"  onclick='ChangeDate(6)'/>7日特价
</td>         
</tr>

<tr> <td colspan="3"> 开始日期： <input id="beginTime" name="beginTime" value="2011-11-25" Onchange="check_radio()"/> </td></tr>
<tr> <td colspan="3"> 结束日期： <input id="endTime" name="endTime" value="2011-11-26"> </td></tr>
</table>
</form>
</body>
</html>