ajax的XMLHttpRequest对象的创建

<script type="text/javascript">
function createXMLHttpRequest()
{
if(window.ActiveXObject)
{
try
{
return new ActiveXObject("MSxml2.XMLHTTP");
}catch(e)
{
return new ActiveXObject("Microsoft.XMLHTTP");
}
}
else if(window.XMLHttpRequest)
{
return new XMLHttpRequest();
}
}

function exec1(v)
{
var xhr=createXMLHttpRequest();
xhr.onreadystatechange=function()
{
if(xhr.readyState==4 && xhr.status==200)
{
document.getElementById("showUser").innerHTML=xhr.responseText;
}
};
xhr.open("post","<%=path%>/getValue.jsp",true);
xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhr.send("deptid="+v);

}
</script>