// document.domain = "caibaojian.com";
function setIframeHeight(iframe) {
if (iframe) {
var iframeWin = iframe.contentWindow || iframe.contentDocument.parentWindow;
if (iframeWin.document.body) {
iframe.height = iframeWin.document.documentElement.scrollHeight || iframeWin.document.body.scrollHeight;
}
}
};

window.onload = function () {
setIframeHeight(document.getElementById('external-frame'));
};

<script language="javascript">
//輸入你希望根據(jù)頁面高度自動調(diào)整高度的iframe的名稱的列表
//用逗號把每個iframe的ID分隔. 例如: ["myframe1", "myframe2"]，可以只有一個窗體，則不用逗號。
//定義iframe的ID
var iframeids=["test"];
//如果用戶的瀏覽器不支持iframe是否將iframe隱藏 yes 表示隱藏，no表示不隱藏
var iframehide="yes";
function dyniframesize()
{
var dyniframe=new Array()
for (i=0; i<iframeids.length; i++)
{
if (document.getElementById)
{
//自動調(diào)整iframe高度
dyniframe[dyniframe.length] = document.getElementById(iframeids[i]);
if (dyniframe[i] && !window.opera)
{
dyniframe[i].style.display="block";
if (dyniframe[i].contentDocument && dyniframe[i].contentDocument.body.offsetHeight) //如果用戶的瀏覽器是NetScape
dyniframe[i].height = dyniframe[i].contentDocument.body.offsetHeight;
else if (dyniframe[i].Document && dyniframe[i].Document.body.scrollHeight) //如果用戶的瀏覽器是IE
dyniframe[i].height = dyniframe[i].Document.body.scrollHeight;
}
}
//根據(jù)設定的參數(shù)來處理不支持iframe的瀏覽器的顯示問題
if ((document.all || document.getElementById) && iframehide=="no")
{
var tempobj=document.all? document.all[iframeids[i]] : document.getElementById(iframeids[i]);
tempobj.style.display="block";
}
}
}
if (window.addEventListener)
window.addEventListener("load", dyniframesize, false);
else if (window.attachEvent)
window.attachEvent("onload", dyniframesize);
else
window.onload=dyniframesize;
</script>

function iframeAutoFit(iframeObj){
setTimeout(function(){if(!iframeObj) return;iframeObj.height=(iframeObj.Document?iframeObj.Document.body.scrollHeight:iframeObj.contentDocument.body.offsetHeight);},200)
}

<iframe src="backtop.html" frameborder="0" scrolling="no" id="test" onload="this.height=100"></iframe>
<script type="text/javascript">
function reinitIframe(){
var iframe = document.getElementById("test");
try{
var bHeight = iframe.contentWindow.document.body.scrollHeight;
var dHeight = iframe.contentWindow.document.documentElement.scrollHeight;
var height = Math.max(bHeight, dHeight);
iframe.height = height;
console.log(height);
}catch (ex){}
}
window.setInterval("reinitIframe()", 200);
</script>

<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;  // 這里通過hash傳遞b.htm的寬高
})();
</script>

<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>

<iframe id="mainFrame" name="mainFrame" src="/zwgk/hsearchview" width="740" frameborder="0" scrolling="no" scrolling="no" frameborder="0" >
</iframe>

<script type="text/javascript" language="javascript">
function reinitIframe(){
 var iframe = document.getElementById("mainFrame");
 try{
 var bHeight = iframe.contentWindow.document.body.scrollHeight;
 var dHeight = iframe.contentWindow.document.documentElement.scrollHeight;
 var height = Math.max(bHeight, dHeight);
 iframe.height = height;
 }catch (ex){}
 }
 window.setInterval("reinitIframe()", 100);
</script>