如果你不需要处理来自不同域的iframe内容，试试这段代码，它将完全解决问题，它很简单:

<script language="JavaScript">
<!--
function autoResize(id){
    var newheight;
    var newwidth;

    if(document.getElementById){
        newheight=document.getElementById(id).contentWindow.document .body.scrollHeight;
        newwidth=document.getElementById(id).contentWindow.document .body.scrollWidth;
    }

    document.getElementById(id).height= (newheight) + "px";
    document.getElementById(id).width= (newwidth) + "px";
}
//-->
</script>

<iframe src="usagelogs/default.aspx" width="100%" height="200px" id="iframe1" marginheight="0" frameborder="0" onLoad="autoResize('iframe1');"></iframe>

如果你不需要处理来自不同域的iframe内容，试试这段代码，它将完全解决问题，它很简单:

<script language="JavaScript">
<!--
function autoResize(id){
    var newheight;
    var newwidth;

    if(document.getElementById){
        newheight=document.getElementById(id).contentWindow.document .body.scrollHeight;
        newwidth=document.getElementById(id).contentWindow.document .body.scrollWidth;
    }

    document.getElementById(id).height= (newheight) + "px";
    document.getElementById(id).width= (newwidth) + "px";
}
//-->
</script>

<iframe src="usagelogs/default.aspx" width="100%" height="200px" id="iframe1" marginheight="0" frameborder="0" onLoad="autoResize('iframe1');"></iframe>

https://developer.mozilla.org/en/DOM/window.postMessage

window.postMessage() window.postMessage is a method for safely enabling cross-origin communication. Normally, scripts on different pages are only allowed to access each other if and only if the pages which executed them are at locations with the same protocol (usually both http), port number (80 being the default for http), and host (modulo document.domain being set by both pages to the same value). window.postMessage provides a controlled mechanism to circumvent this restriction in a way which is secure when properly used. Summary window.postMessage, when called, causes a MessageEvent to be dispatched at the target window when any pending script that must be executed completes (e.g. remaining event handlers if window.postMessage is called from an event handler, previously-set pending timeouts, etc.). The MessageEvent has the type message, a data property which is set to the string value of the first argument provided to window.postMessage, an origin property corresponding to the origin of the main document in the window calling window.postMessage at the time window.postMessage was called, and a source property which is the window from which window.postMessage is called. (Other standard properties of events are present with their expected values.)

iFrame- resizzer库使用postMessage来保持iFrame的大小与其内容一致，并使用MutationObserver来检测内容的变化，而不依赖于jQuery。

https://github.com/davidjbradshaw/iframe-resizer

jQuery:跨域脚本的优点

http://benalman.com/projects/jquery-postmessage-plugin/

有调整iframe窗口大小的演示…

http://benalman.com/code/projects/jquery-postmessage/examples/iframe/

这篇文章展示了如何消除对jQuery的依赖…Plus有很多有用的信息和链接到其他解决方案。

http://www.onlineaspect.com/2010/01/15/backwards-compatible-postmessage/

Barebones操作...

http://onlineaspect.com/uploads/postmessage/parent.html

HTML 5工作草案在window.postMessage

http://www.whatwg.org/specs/web-apps/current-work/multipage/comms.html#crossDocumentMessages

John Resig谈跨窗口消息传递

http://ejohn.org/blog/cross-window-messaging/

iGoogle小工具必须主动实现调整大小，所以我猜在跨域模型中，如果没有远程内容以某种方式参与，你就无法做到这一点。如果您的内容可以使用典型的跨域通信技术将具有新大小的消息发送到容器页面，那么其余部分就很简单了。

This is slightly tricky as you have to know when the iframe page has loaded, which is difficuly when you're not in control of its content. Its possible to add an onload handler to the iframe, but I've tried this in the past and it has vastly different behaviour across browsers (not guess who's the most annoying...). You'd probably have to add a function to the iframe page that performs the resize and inject some script into the content that either listens to load events or resize events, which then calls the previous function. I'm thinking add a function to the page since you want to make sure its secure, but I have no idea how easy it will be to do.

下面是一个简单的解决方案，使用与iframe内容相同的服务器提供的动态生成的样式表。很简单，样式表“知道”iframe中有什么，并且知道用于设置iframe样式的维度。这就绕过了同源策略限制。

http://www.8degrees.co.nz/2010/06/09/dynamically-resize-an-iframe-depending-on-its-content/

因此，所提供的iframe代码将有一个附带的样式表，像这样…

<link href=“http://your.site/path/to/css?contents_id=1234&dom_id=iframe_widget” rel=“stylesheet” type=“text/css” /> <iframe id=“iframe_widget” src=“http://your.site/path/to/content?content_id=1234” frameborder=“0” width=“100%” scrolling=“no”></iframe>

这要求服务器端逻辑能够计算iframe呈现内容的尺寸。