这个答案只适用于使用Bootstrap的网站。Bootstrap的响应式嵌入特性完成了这项工作。它是基于内容的宽度(而不是高度)。

<!-- 16:9 aspect ratio -->
<div class="embed-responsive embed-responsive-16by9">
  <iframe class="embed-responsive-item" src="http://www.youtube.com/embed/WsFWhL4Y84Y"></iframe>
</div>

jsfiddle: http://jsfiddle.net/00qggsjj/2/

http://getbootstrap.com/components/#responsive-embed

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。

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/

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。

使用jQuery的最简单方法:

$("iframe")
.attr({"scrolling": "no", "src":"http://www.someotherlink.com/"})
.load(function() {
    $(this).css("height", $(this).contents().height() + "px");
});

http://www.phinesolutions.com/use-jquery-to-adjust-the-iframe-height.html上的解决方案很好(使用jQuery):

<script type=”text/javascript”>
  $(document).ready(function() {
    var theFrame = $(”#iFrameToAdjust”, parent.document.body);
    theFrame.height($(document.body).height() + 30);
  });
</script>

我不知道你是否需要在长度上加上30…我为我工作过。

仅供参考:如果你已经在你的iFrame上有一个“height”属性，这只是添加了style="height: xxx"。这可能不是你想要的。