Is there a cross-domain iframe height auto-resizer that works?

Question

You have three alternatives:

1. Use iFrame-resizer

This is a simple library for keeping iFrames sized to their content. It uses the PostMessage and MutationObserver APIs, with fall backs for IE8-10. It also has options for the content page to request the containing iFrame is a certain size and can also close the iFrame when your done with it.

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

2. Use Easy XDM (PostMessage + Flash combo)

Easy XDM uses a collection of tricks for enabling cross-domain communication between different windows in a number of browsers, and there are examples for using it for iframe resizing:

http://easyxdm.net/wp/2010/03/17/resize-iframe-based-on-content/

http://kinsey.no/blog/index.php/2010/02/19/resizing-iframes-using-easyxdm/

Easy XDM works by using PostMessage on modern browsers and a Flash based solution as fallback for older browsers.

See also this thread on Stackoverflow (there are also others, this is a commonly asked question). Also, Facebook would seem to use a similar approach.

3. Communicate via a server

Another option would be to send the iframe height to your server and then poll from that server from the parent web page with JSONP (or use a long poll if possible).

I got the solution for setting the height of the iframe dynamically based on it's content. This works for the cross domain content. There are some steps to follow to achieve this.

1. Suppose you have added iframe in "abc.com/page" web page

   <div> <iframe id="IframeId" src="http://xyz.pqr/contactpage" style="width:100%;" onload="setIframeHeight(this)"></iframe> </div>

2. Next you have to bind windows "message" event under web page "abc.com/page"

window.addEventListener('message', function (event) {
//Here We have to check content of the message event  for safety purpose
//event data contains message sent from page added in iframe as shown in step 3
if (event.data.hasOwnProperty("FrameHeight")) {
        //Set height of the Iframe
        $("#IframeId").css("height", event.data.FrameHeight);        
    }
});

On iframe load you have to send message to iframe window content with "FrameHeight" message:

function setIframeHeight(ifrm) {
   var height = ifrm.contentWindow.postMessage("FrameHeight", "*");   
}

3. On main page that added under iframe here "xyz.pqr/contactpage" you have to bind windows "message" event where all messages are going to receive from parent window of "abc.com/page"

window.addEventListener('message', function (event) {

    // Need to check for safety as we are going to process only our messages
    // So Check whether event with data(which contains any object) contains our message here its "FrameHeight"
   if (event.data == "FrameHeight") {

        //event.source contains parent page window object 
        //which we are going to use to send message back to main page here "abc.com/page"

        //parentSourceWindow = event.source;

        //Calculate the maximum height of the page
        var body = document.body, html = document.documentElement;
        var height = Math.max(body.scrollHeight, body.offsetHeight,
            html.clientHeight, html.scrollHeight, html.offsetHeight);

       // Send height back to parent page "abc.com/page"
        event.source.postMessage({ "FrameHeight": height }, "*");       
    }
});

What I did was compare the iframe scrollWidth until it changed size while i incrementally set the IFrame Height. And it worked fine for me. You can adjust the increment to whatever is desired.

   <script type="text/javascript">
    function AdjustIFrame(id) {
        var frame = document.getElementById(id);
        var maxW = frame.scrollWidth;
        var minW = maxW;
        var FrameH = 100; //IFrame starting height
        frame.style.height = FrameH + "px"

        while (minW == maxW) {
            FrameH = FrameH + 100; //Increment
            frame.style.height = FrameH + "px";
            minW = frame.scrollWidth;
        }
    }

   </script>


<iframe id="RefFrame" onload="AdjustIFrame('RefFrame');" class="RefFrame"
    src="http://www.YourUrl.com"></iframe>

I have a script that drops in the iframe with it's content. It also makes sure that iFrameResizer exists (it injects it as a script) and then does the resizing.

I'll drop in a simplified example below.

// /js/embed-iframe-content.js

(function(){
    // Note the id, we need to set this correctly on the script tag responsible for
    // requesting this file.
    var me = document.getElementById('my-iframe-content-loader-script-tag');

    function loadIFrame() {
        var ifrm = document.createElement('iframe');
        ifrm.id = 'my-iframe-identifier';
        ifrm.setAttribute('src', 'http://www.google.com');
        ifrm.style.width = '100%';
        ifrm.style.border = 0;
        // we initially hide the iframe to avoid seeing the iframe resizing
        ifrm.style.opacity = 0;
        ifrm.onload = function () {
            // this will resize our iframe
            iFrameResize({ log: true }, '#my-iframe-identifier');
            // make our iframe visible
            ifrm.style.opacity = 1;
        };

        me.insertAdjacentElement('afterend', ifrm);
    }

    if (!window.iFrameResize) {
        // We first need to ensure we inject the js required to resize our iframe.

        var resizerScriptTag = document.createElement('script');
        resizerScriptTag.type = 'text/javascript';

        // IMPORTANT: insert the script tag before attaching the onload and setting the src.
        me.insertAdjacentElement('afterend', ifrm);

        // IMPORTANT: attach the onload before setting the src.
        resizerScriptTag.onload = loadIFrame;

        // This a CDN resource to get the iFrameResizer code.
        // NOTE: You must have the below "coupled" script hosted by the content that
        // is loaded within the iframe:
        // https://unpkg.com/[email protected]/js/iframeResizer.contentWindow.min.js
        resizerScriptTag.src = 'https://unpkg.com/[email protected]/js/iframeResizer.min.js';
    } else {
        // Cool, the iFrameResizer exists so we can just load our iframe.
        loadIFrame();
    }    
}())

Then the iframe content can be injected anywhere within another page/site by using the script like so:

<script
  id="my-iframe-content-loader-script-tag"
  type="text/javascript"
  src="/js/embed-iframe-content.js"
></script>

The iframe content will be injected below wherever you place the script tag.

Hope this is helpful to someone. 👍