ajax从jsp向servlet传值

function Delete(s){

xmlHttp=new XMLHttpRequest();
var url = "/emp/FindSpecial?selcol=" +s;
xmlHttp.onreadystatechange=state_Change; alert(s);
xmlHttp.open("GET",url,true);
xmlHttp.send(null);

window.location.href="Delete";
}
function state_Change()
{
if (xmlhttp.readyState==4)
{// 4 = "loaded"
if (xmlhttp.status==200)
{// 200 = OK
// ...our code here...
}
else
{
alert("Problem retrieving XML data");
}
}
}