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/

找不到能完美处理大文本+大图像的东西，但我最终得到了这个，似乎这是对的，或者几乎是对的，每一次:

    iframe.addEventListener("load",function(){
        // inlineSize, length, perspectiveOrigin, width
        let heightMax = 0;
        // this seems to work best with images...
        heightMax = Math.max(heightMax,iframe.contentWindow.getComputedStyle(iframe.contentWindow.document.body).perspectiveOrigin.split("px")[0]);
        // this seems to work best with text...
        heightMax = Math.max(heightMax,iframe.contentWindow.document.body.scrollHeight);
        // some large 1920x1080 images always gets a little bit off on firefox =/
        const isFirefox = navigator.userAgent.toLowerCase().indexOf('firefox') > -1;
        if(isFirefox && heightMax >= 900){
            // grrr..
            heightMax = heightMax + 100;
        }

        iframe.style.height = heightMax+"px";
        //console.log(heightMax);
    });

我相信这样的做法会奏效。

parent.document.getElementById(iFrameID).style.height=framedPage.scrollHeight;

在iframe内容中加载你的body。

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

https://getbootstrap.com/docs/4.0/utilities/embed/

经过大量的研究，我明白了，这不是一个独特的问题，我打赌Bootstrap处理它。你瞧……