子页面头部是：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<iframe id="mainFrame" name="mainFrame" scrolling="no" src="Index.aspx"
frameborder="0" style="padding: 0px; 100%; height: 1000px;"></iframe>
父页面调用：
<script type="text/javascript">
startInit('mainFrame', 560);
</script>
<script>
var browserVersion = window.navigator.userAgent.toUpperCase();
var isOpera = browserVersion.indexOf("OPERA") > -1 ? true : false;
var isFireFox = browserVersion.indexOf("FIREFOX") > -1 ? true : false;
var isChrome = browserVersion.indexOf("CHROME") > -1 ? true : false;
var isSafari = browserVersion.indexOf("SAFARI") > -1 ? true : false;
var isIE = (!!window.ActiveXObject || "ActiveXObject" in window);
var isIE9More = (! -[1,] == false);
function reinitIframe(iframeId, minHeight) {
try {
var iframe = document.getElementById(iframeId);
var bHeight = 0;
if (isChrome == false && isSafari == false) {
try {
bHeight = iframe.contentWindow.document.body.scrollHeight;
} catch (ex) {
}
}
var dHeight = 0;
if (isFireFox == true)
dHeight = iframe.contentWindow.document.documentElement.offsetHeight + 2;//如果火狐浏览器高度不断增加删除+2
else if (isIE == false && isOpera == false && iframe.contentWindow) {
try {
dHeight = iframe.contentWindow.document.documentElement.scrollHeight;
} catch (ex) {
}
}
else if (isIE == true && isIE9More) {//ie9+
var heightDeviation = bHeight - eval("window.IE9MoreRealHeight" + iframeId);
if (heightDeviation == 0) {
bHeight += 3;
} else if (heightDeviation != 3) {
eval("window.IE9MoreRealHeight" + iframeId + "=" + bHeight);
bHeight += 3;
}
}
else//ie[6-8]、OPERA
bHeight += 3;
var height = Math.max(bHeight, dHeight);
if (height < minHeight) height = minHeight;
//alert(iframe.contentWindow.document.body.scrollHeight + "~" + iframe.contentWindow.document.documentElement.scrollHeight);
iframe.style.height = height + "px";
} catch (ex) { }
}
function startInit(iframeId, minHeight) {
eval("window.IE9MoreRealHeight" + iframeId + "=0");
window.setInterval("reinitIframe('" + iframeId + "'," + minHeight + ")", 100);
}
</script>
参考：https://www.cnblogs.com/slyzly/articles/2422737.html