HTML中的alert的运用,帮帮忙
<%@   page   language= "java "   pageEncoding= "ISO-8859-1 "%>  
  <%@   taglib   uri= "http://struts.apache.org/tags-bean "   prefix= "bean "   %>  
  <%@   taglib   uri= "http://struts.apache.org/tags-html "   prefix= "html "   %>  
  <%@   taglib   uri= "http://struts.apache.org/tags-logic "   prefix= "logic "   %>  
  <%@   taglib   uri= "http://struts.apache.org/tags-tiles "   prefix= "tiles "   %>  
  <html>  
        <head>  
              <title> MyJsp.jsp </title>  
              <script   type= "text/javascript ">  
 			function   al() 
 			{ 
 				alert(radio1.value); 
 			} 
              </script>  
  </head>  
  <body>  
  <table   width= "100% "   border= "1 "   height= "40% "> 	 
 	 <tr>  <td   align=center   width= "40% "   height=400>  
 	 <table>  
 	  <tr>  <td>  <strong> 请输入编号 </strong>  <br>  <input   type=text   name=number   />  </td>  </tr>  
                     </table>  
 	       </td>  
  <td>  <strong> 点击选择类型 </strong>  
   <br>  <input   type= "radio "   name= "radio1 "   checked=checked   value= "A "   /> A 
   <br>  <input   type= "radio "   name= "radio1 "   value= "B "   /> B 
   <br>  <input   type= "radio "   name= "radio1 "   value= "C "   /> C 
   <br>  
   <br>  <input   type=button   name=cancle   value= "取消 "/>  
     <input   type=button   name=next   value= "上一步 "   />  
                    <input   type=button   name=next   value= "进入 ";   onclick= "al() "   />  
  </td>  </tr>  
  </table>  
     </body>  
  </html>      
 我按了进入按钮后,就提示undefine,请问一下哪里错了? 
------解决方案-------------------- <script>  
 function b() 
 { 
 	o = document.getElementsByName( "a "); 
 	for(c=0;c <o.length;c++) 
 	{ 
 		if(o[c].checked) alert(o[c].value); 
 	} 
 } 
  </script>  
  <input type= "radio " name= "a " value= "a ">  
  <input type= "radio " name= "a " value= "b ">  
  <input type= "radio " name= "a " value= "c ">  
  <input type= "button " onclick= "b() ">
------解决方案-------------------- <!DOCTYPE html PUBLIC  "-//W3C//DTD XHTML 1.0 Transitional//EN "  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">  
  <html xmlns= "http://www.w3.org/1999/xhtml ">  
  <head>  
  <meta http-equiv= "Content-Type " content= "text/html; charset=gb2312 " />  
  <title> 无标题文档 </title>  
      <script type= "text/javascript ">  
 			function al() 
 			{ 
 				var radio1 = document.getElementsByTagName( &q