function createXMLHttpRequest() {
var xmlHttp = null;
if (window.XMLHttpRequest) {
    xmlHttp = new XMLHttpRequest();
}
else if (window.ActiveXObject) {
    xmlHttp = new ActiveXObject("Microsoft.XMLHTTP")
}
if (xmlHttp == null) return


data = "a=1&b=1"
xmlHttp.onreadystatechange = handleStateChange;
xmlHttp.open("POST", "simpleResponse.ashx?tmp=" + (new Date()).valueOf(), true);
xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlHttp.setRequestHeader("Content-length", data.length);
xmlHttp.setRequestHeader("Connection", "close");
xmlHttp.send(data);
}
function handleStateChange() {
if (xmlHttp.readyState == 4) {
    if (xmlHttp.status == 200) {
        alert(xmlHttp.responseText);
    }
}
}