ajax中的xmlHttp.readyState == 1这步在chrome浏览器中没有执行咋回事

<SCRIPT type="text/javascript">
<!--
    var xmlHttp = "";
    function creatXMLHttpRequest() {
        if   (window.XMLHttpRequest)   {   //   Mozilla,   Safari,...  
            xmlHttp =new XMLHttpRequest();              
        }  
        else if(window.ActiveXObject)   {   //   IE   
            xmlHttp =new ActiveXObject("Msxml2.XMLHTTP");   
        }    
    }

    function startRequest() {
        var queryString;
        var domain = document.getElementById('domain').value;
        queryString = "domain=" + domain;
        creatXMLHttpRequest();
        xmlHttp.open("POST","?action=do","true");
        xmlHttp.onreadystatechange = handleStateChange;
        xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded;");
        xmlHttp.send(queryString);
    }

    function handleStateChange() {
        if(xmlHttp.readyState == 1) {
            document.getElementById('result').style.cssText = "";
            document.getElementById("result").innerHTML="正在查询……";
        }
        if(xmlHttp.readyState == 4) {
            if(xmlHttp.status == 200) {
                document.getElementById('result').style.cssText = "";
                var allcon =  xmlHttp.responseText;
                document.getElementById('result').innerHTML = allcon;
            }
        }
    }
 
//-->
</SCRIPT>