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.

7,966 thoughts on “iframe automatic height adjustment using HTML5 cross domain web messaging”

  6. This article empowers readers with knowledge they wouldn’t typically think about until faced with adversity—I applaud you for tackling tough topics!! # # anyKey word ## Biohazard Clean Up

  10. рейтинг casino онлайн рулетка Хотите играть в казино где надежность сочетается с мгновенным выводом? Вы нашли то что искали Мы предлагаем лучшие площадки где ваши деньги в безопасности а получение выигрышей происходит максимально быстро. Играйте с уверенностью

  16. It’s refreshing to see phone stores using trade-in programs that make updating easier and more cost effective! If you’re considering one, take a look at the options readily available at free phones !

  23. и Антошке пару точек купить кокаин мефедрон гашиш бошки Сатка посмотри в трипах магазина там всё написано

  25. I absolutely love how fashion jewelry can transform a whole outfit! It’s amazing how a basic piece can include a lot elegance and character. Have you ever thought about personalizing your own jewelry? It can produce a truly unique declaration piece buy gold denver co

  30. Промокод 1xBet при регистрации. Компания 1XBET заинтересована в расширении аудитории поэтому для новых пользователей действует акция в виде первого подарка который равен сумме первого депозита но не превышает 225 000 рублей. Однако при использовании промокод 1хБет при регистрации букмекерская контора увеличит размер приветственного бонуса. Чтобы получить дополнительное вознаграждение на первый депозит игроку нужно: зайти на сайт букмекера выбрать создание аккаунта через почту заполнить данные ввести промокод и подтвердить согласие с правилами. Промокод 1xBet помогает получить ещё больше бонусов. Это набор символов которая позволяет активировать уникальный бонус от букмекера. С его помощью можно получить фрибет и другие подарки.

  33. Martial arts not just enhance physical fitness but also impart technique and emphasis in experts. It’s fascinating to see exactly how various styles, from martial arts to jiu-jitsu, offer unique benefits Denver TaeKwonDo

  40. Компания https://prometall.shop/ предлагает широкий ассортимент качественных банных печей, которые превратят вашу парную в настоящий оазис релаксации. Здесь представлены модели для любых размеров помещений — от компактных семейных бань до просторных коммерческих саун. Каждая печь изготовлена из жаропрочной стали с увеличенным сроком службы, обеспечивает быстрый и равномерный прогрев, а также экономичный расход топлива. Профессиональные консультанты помогут подобрать оптимальный вариант под ваши требования и бюджет.

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>