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.

7,917 thoughts on “iframe automatic height adjustment using HTML5 cross domain web messaging”

  1. Great observations made surrounding developing an online presence centered around natural user acquisition methods proven effective thanks largely due contributions made by firms such as #WebJuice#-I’ll look further into ### anykeyword ###!! Organic leads generation

  3. Grateful understanding there’s anybody who cares in truth approximately buyer pride general!!!Explore trending discussions going down excellent now simply by: ### anyKeyWord ### Plumber Norwich

  7. Автором книг является человек который создает литературные произведения такие как романы рассказы или стихи. Чаще всего таких людей называют писателями поэтами или литераторами. Buchautorin— это создатель произведения чьим творческим трудом оно создано

  8. ЦВЗ центр https://cvzcentr.ru в Краснодаре — команда специалистов которая работает с вегетативными расстройствами комплексно. Детальная диагностика сопровождение пациента и пошаговый план улучшения самочувствия.

  9. ЦВЗ центр https://cvzcentr.ru в Краснодаре — команда специалистов которая работает с вегетативными расстройствами комплексно. Детальная диагностика сопровождение пациента и пошаговый план улучшения самочувствия.

  15. Nairabet offers https://nairabet-play.com sports betting and virtual games with a simple interface and a wide range of markets. The platform provides live and pre-match options quick access to odds and regular updates. Visit the site to explore current features and decide if it suits your preferences.

  16. Nairabet offers https://nairabet-play.com sports betting and virtual games with a simple interface and a wide range of markets. The platform provides live and pre-match options quick access to odds and regular updates. Visit the site to explore current features and decide if it suits your preferences.

  24. It’s amazing how a creative design on a simple business card can leave such a strong impression. I’ve used Print FX for custom print projects and discovered Direct Mail Services through their team—so convenient!

  34. I hadn’t considered how tactile paper choices can impact a restaurant’s vibe. Textured stock can make a huge difference. If anyone is interested in exploring more options, Decals and Stickers and Print FX are worth checking out.

  38. Автором книг является человек который создает литературные произведения такие как романы рассказы или стихи. Чаще всего таких людей называют писателями поэтами или литераторами. Buchautor— это создатель произведения чьим творческим трудом оно создано

  44. Автором книг является человек который создает литературные произведения такие как романы рассказы или стихи. Чаще всего таких людей называют писателями поэтами или литераторами. Schriftsteller— это создатель произведения чьим творческим трудом оно создано

  48. зашел на сайт не нашел там 307 купить кокаин мефедрон гашиш бошки Магадан А вообще читай раздел рецепты там все очень подробно расписано в нескольких темах причем

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>