iframe的子页面怎样操作父页屏蔽页面弹出层效果

<!-- 右侧iframe开始 --> 
<div id="resDiv" class="resDiv"> 
<iframe name="res" class="iframestyle" allowtransparency="true" src="son.html" frameborder="0" scrolling="no"></iframe> 
</div> 
<!-- 右侧iframe结束 -->

<!--弹出的登录页面层--> 
<div id="mapLayer" style="display: none; " > 
<input type="button" value="关闭" onclick="closeMap()" /> 
</div> 
<!--屏蔽层，用来透明的屏蔽整个页面--> 
<div id="mapBgLayer" style="position:absolute; display: none;"></div>

<style type="text/css"> 
#BgLayer { 
background: #939393 none repeat scroll 0 0; 
height:100%; 
width:100%; 
left:0; 
top:0; 
filter: alpha(opacity=80); /* IE */ 
-moz-opacity: 0.8; /* Moz + FF */ 
z-index: 10000; 
} 
#Layer { 
width: 400px; 
height: 400px; 
margin: -180px 0 0 -170px; 
left: 50%; 
top: 50%; 
position: absolute; 
background: #FFF; 
z-index: 10001; 
border: 1px solid #1B5BAC; 
} 
</style> 
<script type="text/javascript"> 
/*显示页面*/ 
function showDiv) { 
var bg = document.getElementById("BgLayer"); 
var con = document.getElementById("Layer"); 
//var w = document.documentElement.clientWidth; //网页可见区域宽 
//var h = document.documentElement.clientHeight;//网页可见区域高 
var w = document.body.scrollWidth; //网页正文全文宽 
var h = document.body.scrollHeight; //网页正文全文高 
// alert(w+"-"+h); 
bg.style.display = ""; 
bg.style.width = w + "px"; 
bg.style.height = h + "px"; 
con.style.display = ""; 
} 
/*关闭*/ 
function closeDiv() { 
var bg = document.getElementById("BgLayer"); 
var con = document.getElementById("Layer"); 
bg.style.display = "none"; 
con.style.display = "none"; 
} 
</script>

<a href="javascript:void(0)" onclick="parent.window.showDiv()">查看</a>