ajax异步处理

function doStop(id,parentNodeObj){
    if(confirm("确实要停止吗？")){
        var str="<div width='100%' align='center'><image src='<%=request.getcontextpath()%>/img/loading4.gif'></image></div>";
        parentNodeObj.innerHTML=str;
        var xhr=createXMLRequest();
        if (xhr!=null)
        {
            xhr.onload=function()
            {
                window.location="<%=request.getcontextpath()%>/testManage_showEnvInstance";
            }
            xhr.open("post","<%=request.getcontextpath()%>/experimentManage_stopExperimentEnv?deploymentId_="+id,true);
            xhr.send(null);
        }
        else
        {
            document.forms[0].method ='post';
            document.forms[0].action="<%=request.getcontextpath()%>/experimentManage_stopExperimentEnv?deploymentId_="+id;
            document.forms[0].submit();	
        }
    }
}