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.

11,834 thoughts on “iframe automatic height adjustment using HTML5 cross domain web messaging”

  5. Довольно сильно жгёт слизистую носа купить онлайн мефедрон экстази бошки Хороший магазин тоже не раз уже к нему обращался я считаю что этот магазин достоин огромного внимание Мир тебе бро и процветания удачи в работе :o k:;ОБРАЩУСЬ ЕЩЕ К ТЕБЕ БРО ОБЯЗАТЕЛЬНО ЕЩЕ РАЗ УДАЧИмесяц назад

  13. For induction compatibility throughout appropriate rated cookware brands, the main points should be would becould very well be buried. I rely on top cookware brands 2023 to ensure which traces on the contrary paintings effectively with induction cooktops.

  22. This is really interesting, You’re a very skilled blogger.
    I’ve joined your rss feed and look forward to seeking more
    of your excellent post. Also, I have shared your site in my social networks!

  27. Где можно найти деньги в бодиграфе? Где деньги в дизайне человека. Дизайн Человека Human Design — расчёт карты по дате рождения онлайн. Кто ты? Инструкция чтобы понять кто ты. Лидерский потенциал. Дизайн Человека выделает пять энергетических типов: Манифестор Манифестирующий Генератор Генератор Проектор и Рефлектор. Найдите сферу где ваши уникальные навыки будут признаны. Почему у генераторов мало денег и как это исправить? Как мотивировать опытных коллег и сохранять авторитет. Что отличает каждый Тип личности в Дизайне человека. Как получать деньги в свою жизнь без надрыва и сопротивления. https://c-human-design-svd-ru-irk.hdsb.ru

  29. My kid’s exhilaration in opposition t getting to know necessarily shines by after institution; I’m pleased seeing newfound passions emerge quickly because of these interactions inside of friends/education approaches alike !! ### anyKeyWord### preschool aurora

  41. a href=”https://pureforeststudio.shop/” />forestcraftstore – Smooth interface with neatly presented items, shopping was simple.

  48. I recently underwent a sinus lift procedure; I’m still amazed by how well everything turned out thanks largely due diligence performed diligently executed competently managed professionally overseen superb supervision garnered courtesy provided gracious Invisalign

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>