iframe automatic height adjustment using HTML5 cross domain web messaging

Posted on by

Yesterday I was working on a site that needed an iframe embedded in the page whose content came from a completely different domain. I try to steer clear of iframes at all costs normally so forgive me if what I’m about to say is pretty obvious.

I didn’t want the content in the iframe to appear as though it was in an iframe, so obviously I stripped off all the default browser styles…well, the border. I wanted the iframe to be as high as the content it was containing so that no scroll bars would appear.

So what I did was just give the iframe a height, however when the user navigated to a different page within the iframe, the height I had previously set was too big or too small.

I instantly thought “right, JavaScript will sort this out for me!” and proceeded to quickly code up a function that would inspect the scrollHeight of the content in the iframe and adjust the iframe height accordingly.

No! Said cross domain policy. I had momentarily forgotten all about that. Since the iframe content came from a different domain, I wasn’t allowed to access the document object of the iframe (or vice versa).

Here is how not to do it

Firefox says “Error: Permission denied to access property ‘document’” and other browsers similar.

I started searching for some kind of workaround.  Of course there isn’t really one…except I did find an interesting hack for Firefox. Which is – an iframe document can alter the url fragment of the parent window’s location object! ha madness.

The idea is that the document in the iframe alters the url fragment to read:

http://freestyle-developments.co.uk/blog/?p=150#138

Where 138 is the height of the iframe document (obviously you could be a bit more fancy and send other parameters and name them e.g #height:138 but for simplicity I’ve just set the value). The parent then reads this value and sets the iframe height accordingly:

var iFrameHeight = parseInt(location.hash.replace('#', ''));

So…yeah, that’s pretty interesting, but not really a solution. Check out the example implementation here.

Anyway, what to do? HTML5 web messaging to the rescue! Sweet! HTML5 web messaging is cross domain messaging done right. Not only does the messenger choose who should receive messages, but the recipient also chooses who to receive messages from.

The idea is that after the iframe document has loaded, it sends a message to the parent window telling it what it’s scrollHeight is. The parent listens for messages, and sets the height of the iframe when it receives a message.

A couple of things to note:

  1. There has to be communication between the two documents. i.e. the document on the external domain needs to actively send this message. Which can be a complete show stopper if you have no control over the document on the external domain
  2. This isn’t going to work on IE < 9. I tested the implementation linked below is working on FireFox 4 (Beta 7), Safari 5.0.2, Chrome 8, Opera 10.63 and Internet Explorer 9 Platform Preview 7. Which is a pretty good spread to be honest

Check out the example HTML5 web messaging implementation here.

11,794 thoughts on “iframe automatic height adjustment using HTML5 cross domain web messaging”

  6. Именно. Основной упор на старых проверенных оптовиков. К сожалению с розницей тут напряг увы купить Мефедрон Бошки Марихуану клады по мск все во времяДом рядом с адресом говоришь отдаешь залог когда приедешь в адрес в разных такси по-разному могут и не попросить и идешб себе за кладом :

  10. Ah, the infamous No Claims Bonus (NCB) – the small print no one reads until they need it. If you’re coming from the UK to the US, don’t expect a seamless transfer of that golden NCB status. US insurers treat it about as seriously as a soggy biscuit no claims discount explained

  16. The adaptability of backyard decks is fantastic! You can tailor them to fit any design or function you need. I recently found some innovative ideas for multi-level decks at deck builders that could actually elevate your outside area.

  23. Использование контрактной разработки позволяет создавать устройства для промышленной автоматизации умных домов и IoT-систем. Все этапы разработки проектирование создание прототипов тестирование и серийное производство контролируются специалистами что обеспечивает высокое качество по ссылке

  25. Your approach towards understanding consumer behavior’s effect on searches was enlightening—I have linked it back to concepts discussed earlier @ ### anyKeyWord### ! AI SEO

  30. Седня 28.04.2014 Чяс назат звонок на телифон говарят курьер это будти дома шяс приеду вашу посылку пренесу я иму несити стук в дверь открываю дверь ом распишитесь получити расписался даю иму паспорт он мне вответ ненужен мне паспорт. https://teploceramic.biz я вот тоже дождался и пришел ко мне груз ценный завтра поеду забирать потом отпишу что и какЭто ошибка или нет подскажи пожалуйста.

  35. 1. 井波優子さんのVoicy、本当に最高です！毎晩寝る前に聴いてるんですけど、優しい声がすごくリラックスできてすぐ眠れちゃうんですよね。なんだか癒されながら1日を終えられる感じ、やっぱり彼女の魅力だなぁって思います。これからも続けてほしいです！

    2. そういえば、井波優子さんが劇団万華鏡での舞台に出演されていたって聞いたんですけど、どんな役をされていたんでしょう？昔の舞台のお話とか聞けたらうれしいなぁ。舞台上での彼女の表情とかすごく気になるので、もっと知りたいです！

    3 maruchan.inaba_yuko

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>