AJax's Call In Javascript?

var Url="getData.aspx?AjaxCall=1&Mode=DelType";
    var SavedResult=postXML(objXMLdom,Url);

function postXML(ObjXMLDom,URL)
{
var objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP");
var strHTTP=URL;
objXMLHttp.open("POST",strHTTP,false);
objXMLHttp.send(ObjXMLDom);
	if(objXMLHttp.responseText != "")
		{
			return (objXMLHttp.responseText);
		}
}