a.html中包含iframe:<iframe src="http://www.b.com/c.html" id="Iframe" frameborder="0" scrolling="no" style="border:0px;"></iframe>
在c.html中加入如下程式碼：<iframe id="c_iframe"  height="0" width="0"  src="http://www.a.com/agent.html" style="display:none" ></iframe>
<script type="text/javascript">
(function autoHeight(){
var b_width = Math.max(document.body.scrollWidth,document.body.clientWidth);
var b_height = Math.max(document.body.scrollHeight,document.body.clientHeight);
var c_iframe = document.getElementById("c_iframe");
c_iframe.src = c_iframe.src + "#" + b_width + "|" + b_height;  // 這裡通過hash傳遞b.htm的寬高
})();
</script>
最後，agent.html中放入一段js:<script type="text/javascript">
var b_iframe = window.parent.parent.document.getElementById("Iframe");
var hash_url = window.location.hash;
if(hash_url.indexOf("#")>=0){
var hash_width = hash_url.split("#")[1].split("|")[0]+"px";
var hash_height = hash_url.split("#")[1].split("|")[1]+"px";
b_iframe.style.width = hash_width;
b_iframe.style.height = hash_height;
}
</script>