弹出层并屏蔽父窗口(防刷新、后退、关闭窗口)

 <script type="text/javascript" language="javascript">
   document.onmouseover=function(){
     if(event.srcElement.id != "tijiao"){
  window.onbeforeunload = function(){
      return "如果您离开本页面，那么您本次的操作将视为无效！";
  }
     }
     else{
  window.onbeforeunload = null;
     }
 };
 function ShowNo()                        //隐藏两个层
        {
            document.getElementById("doing").style.display="none";
            document.getElementById("loading").style.display="none";
        }
        function $(id)        
        {
            return (document.getElementById) ? document.getElementById(id) : document.all[id] ;
        }
        function showFloat()                    //根据屏幕的大小显示两个层
        {
            var range = getRange();
            $('doing').style.width = range.width + "px";
            $('doing').style.height = range.height + "px";
            $('doing').style.display = "block";
            document.getElementById("loading").style.display="";
        }
        function getRange()                      //得到屏幕的大小
        {
              var top     = document.body.scrollTop;
              var left    = document.body.scrollLeft;
              var height  = document.body.clientHeight;
              var width   = document.body.clientWidth;

              if (top==0 && left==0 && height==0 && width==0)
              {
                top     = document.documentElement.scrollTop;
                left    = document.documentElement.scrollLeft;
                height  = document.documentElement.clientHeight;
                width   = document.documentElement.clientWidth;
              }
              return  {top:top  ,left:left ,height:height ,width:width } ;
        }
    </script>
    <style type="text/css"> 
            body{margin:0px;}
    </style>

<form id="form1" runat="server">
    <a id="tijiao" href="javascript:void(0)" onclick="showFloat()">提交</a>
    <div style="margin:auto;height:500px; width:300px;text-align:center;line-height:500px;">此处添加表单信息</div>   

    <!--加一个半透明层-->
    <div id="doing"  style="filter:alpha(opacity=30);-moz-opacity:0.3;opacity:0.3;background-color:#000;width:100%;height:100%;z-index:1000;position: absolute;left:0;top:0;display:none;overflow: hidden;">
    </div>   
    <!--加一个等待层-->
    <div id="loading" style="border:solid 10px #898989;background:#fff;padding:10px;width:780px;z-index:1001; position: absolute; display:none;top:50%; left:50%;margin:-200px 0 0 -400px;">
            <div style="padding:3px 15px 3px 15px;text-align:left;vertical-align:middle;" >
                <div>
                    数据正在请求中，请稍等...
                </div>
            </div>
      </div>
    </form>