ajax向后台传参!!

 1     <script type="text/javascript">
 2         function Myupdate(btn)
 3     {
 4          var btnId=btn.id;  //获取button的ID
 5          var Ubtn=document.getElementById(btnId); //获取button对象
 6          var tablerow=Ubtn.parentNode.parentNode;  //取得button所在的行对象
 7          var fChild=tablerow.getElementsByTagName("td")[0]; //找到对应行的TD对象
 8 
 9          var strHtml="<input type='text' id='kao'>"
10          fChild.innerHTML=strHtml;
11          fChild.focus();
12 
13     }    
14     
15     function Mydelete(btn)
16    {
17         //总行数
18         var tNum=document.all('table1').rows.length;
19         //行数
20         var rowNum=btn.id;
21 
22         //时间
23         var now= new Date();
24         var year=now.getYear();
25         var month=now.getMonth()+1;
26         var day=now.getDate();
27         var hour=now.getHours();
28         var minute=now.getMinutes();
29         var second=now.getSeconds();
30         var datetime=year+"-"+month+"-"+day+" "+hour+":"+":"+minute+":"+second; 
31         
32         var xhr;
33        if (window.XMLHttpRequest) {
34         xhr = new XMLHttpRequest();
35         }
36         else if (window.ActiveXObject) {
37         xhr = new ActiveXObject("Msxml2.XMLHTTP");
38         }
39         else {
40             throw new Error("error,fuck");
41         }
42 
43            var url="Default.aspx?rowNum="+rowNum+"&dateTime="+datetime;
44            xhr.open("get",url,true);
45             //xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
46            xhr.send(null); 
47            xhr.onreadystatechange= function()
48             {
49                  if (xhr.readyState == 4||xhr.readyState=='complate')
50                  {
51                     if (xhr.status >= 200 && xhr.status < 300)
52                     {
53                         var theText=xhr.responseText;
54                         alert(theText);
55                     }
56                 }
57              }
58    }
59