使用XmlHttp实现等待页面

       开发的系统需要做到良好的客户体验，点击之后又一个等待的图片显示，利用XmlHttp可以实现。
       主要js代码如下：
      

 var result;
                  var content = "<table height=100% width=100%><tr><td><div id='divDoing' style='position:absolute; left:"+(screen.availWidth-500)/2+"px; top:136px; width:196px; height:105px; z-index:1;'><div align='center'><p><img src='../Images/doing.gif' width='32' height='32'/></p><p><br/>正在发送邮件,请稍候……</p></div></div></td></tr></table>";
    contentTD.innerHTML = content;
        var XmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
    XmlHttp.onreadystatechange=function(){
        if(XmlHttp.readyState==4){
            if(XmlHttp.status==200)
            {
              result = XmlHttp.responseText;
              //alert(result);
              if(result=="OK")
                  { 
                    alert("邮件已经提交邮件服务器！");
                    location.href ="../Library/webinitPage.tkx?Source=SendResult";
                  }
                 else
                 {
                   alert("有错误发生，请重新发送。若还发送不成功请联系管理员!"); 
                   location.href ="../Library/webinitPage.tkx?Source=MailSend";
                 }  
                        
                 }
            }
            else
            contentTD.innerHTML = content ;
        }
    }
    XmlHttp.open("post","webinitPage.tkx?Source=MailSend",true);
    XmlHttp.send(xml);