Js获取radiobuttonlist选中值完整代码

<% @ Page language = " c# "  Codebehind = " WebForm1.aspx.cs "  AutoEventWireup = " false "  Inherits = " ajaxselect.OnmouseTitle.WebForm1 "  %>
<! DOCTYPE HTML PUBLIC  " -//W3C//DTD HTML 4.0 Transitional//EN "  >
< HTML >
     < HEAD >
         < title > WebForm1 </ title >
         < meta content = " Microsoft Visual Studio .NET 7.1 "  name = " GENERATOR " >
         < meta content = " C# "  name = " CODE_LANGUAGE " >
         < meta content = " JavaScript "  name = " vs_defaultClientScript " >
         < meta content = " http://schemas.microsoft.com/intellisense/ie5 "  name = " vs_targetSchema " >
         < script language = " javascript " >
        
                function  getvalue()
         {
        var b=document.all.rbtid.length
        var a=document.getElementById("rbtid").rows.length; 
        //alert(b);结果为5
        //alert(a);结果为4
        //for(var i=0;i<b-1;i++)这样也行
        for(var i=0;i<a;i++)
        {
          var ss="rbtid_"+i;
          var aa=document.getElementById(ss).value;
          //if(eval('document.all.rbtid_'+i).checked==true) //这样也行 eval()函数能将数据符串转成js运行
          var bb=document.getElementById(ss);
          if(document.getElementById(ss).checked)  //注意checked不能写成Checked，要不然不成功
           {
                  alert(aa);
                  break;
           }      
        
        }
        }
         </ script >
     </ HEAD >
     < body MS_POSITIONING = " GridLayout " >
         < form id = " Form1 "  method = " post "  runat = " server " >
             < FONT face = " 宋体 " >
                 < asp:radiobuttonlist id = " rbtid "  style = " Z-INDEX: 101; LEFT: 8px; POSITION: absolute; TOP: 8px "  runat = " server "
                    Width = " 216px "  Height = " 176px "  name = " rbtid " >
                     < asp:ListItem Value = " 0 " > 0 </ asp:ListItem >
                     < asp:ListItem Value = " 1 "  Selected > 1 </ asp:ListItem >
                     < asp:ListItem Value = " 2 " > 2 </ asp:ListItem >
                     < asp:ListItem Value = " 3 " > 3 </ asp:ListItem >
                 </ asp:radiobuttonlist >< INPUT style = " Z-INDEX: 102; LEFT: 184px; POSITION: absolute; TOP: 256px "  onclick = " getvalue() "
                    type = " button "  value = " Button " ></ FONT >
         </ form >
     </ body >
</ HTML >