如何动态改变input type=submit 的type属性为button

1. <form name="form1" action="1.htm">
   
2. <input>
   
3. <input type="submit" name="t1">
   
4. </form>
   
5. <script language="JavaScript">
   
6. alert(form1.t1.type);
   
7. form1.t1.removeNode(true);
   
8. var s=document.createElement('INPUT');
   
9. s.type='button';
   
10. s.value='Submit';
    
11. s.attachEvent('onclick',function(){form1.submit()});
    
12. form1.appendChild(s);
    
13. </script>