ajax非同步呼叫過程

JS代碼：

function example(){   var req = getReq();   req.open("GET", "QuerybyActionSample.aspx?name=" + escape(Name), true);   req.onreadystatechange = function() {   if (req.readyState == 4) {             str = req.responseText;             showMessage(str);        }    };    req.send(null);}               function getReq() {    var oHttpReq = null;    if (window.ActiveXObject)         {oHttpReq = new ActiveXObject("MSXML2.XMLHTTP");}    else if (window.createRequest)         {oHttpReq = window.createRequest();}    else         {oHttpReq = new XMLHttpRequest();}    return oHttpReq;}

註：escape()避免了後台獲得前台頁面值的亂碼問題。