ajax小例子 鼠标移动菜单 显示详细信息

就是鼠标移动到gridview的某一行，通过行的id显示详细信息
这个效果是纯JS，信息内容用ajax获取
<tr onmouseover="showdetails(3)"></tr>//gridview编译后的html
function showdetails(id)
{
var url = "getdata.aspx?id="+id;
var req = getAjax();
req.open("GET", url, true);
req.onreadystatechange = function(){
if(req.readyState==4){
var re = req.responseText;//获取返回的内容
}
};
req.send(null);
}
function getAjax()
{
var oHttpReq = null;
if(window.ActiveXObject)
oHttpReq = new ActiveXObject("MSXML2.XMLHTTP");
else if(window.createRequest)
oHttpReq = window.createRequest();
else
oHttpReq = new XMLHttpRequest();
return oHttpReq;
}