iframe automatic height adjustment using HTML5 cross domain web messaging

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.

11,688 thoughts on “iframe automatic height adjustment using HTML5 cross domain web messaging

  1. магазина в скайпе не поймать?как можно с вами пообщаться? купить скорость кокаин мефедрон гашиш может я не вполне в темеи с спрс работаю 2 разно ни одна из известных мне почтовых служб не доставляла отправление до адресата за 4000 вёрст за 3-4 днякак это делает спрс. а насчёт :police: просто смешно – захотят принять – примут по-любомухоть с почтовым голубем.: доставка дороговатано это самое меньшее из возможных зол.Че за доверенный магазин мля Кто нах его в доверенные записал? Админы убирайте его нах Заказал товар отправляли неделю потом трек ждал завтраками кормили счас трек не бьется 3 день ася оффлайн бросик отошел- на сообщения не отвечает Люди не заказывайте тут ничего

  2. Точная маркировка оборудования, табличек и шильдов давно стала обязательным стандартом для промышленности, и лазерная гравировка уверенно вытеснила менее надёжные технологии. На странице https://inpekmet.ru/lazernaia-gravirovka компания «Инпек» рассказывает о возможностях высокоточной гравировки по металлу любой сложности и бесплатно изготавливает образец шильдика по заявке. Клиенту достаточно отправить макет или поручить его разработку специалистам, чтобы получить чёткие, износостойкие надписи и изображения, устойчивые к времени, агрессивной среде и механическим воздействиям — важный фактор для производства, логистики и оборудования.

  3. Пошаговое руководство описывает как попасть на кракен используя правильную последовательность: загрузка Tor проверка цифровой подписи установщика настройка мостов для обхода блокировок.

  4. Fighting style not only boost physical conditioning but also infuse self-control and emphasis in specialists. It’s remarkable to see just how different designs, from martial arts to jiu-jitsu, offer special advantages Denver TaeKwonDo classes

  5. Bay Area Rodent Solutions made our lives so much easier with their top-notch rodent control services
    I am genuinely impressed by the results from Bay Area Rodent Solutions and their effective rodent control solutions
    If you want peace of mind rat removal Cambrian neighborhood

  6. Love that you just outlined administrative center motels. After my analysis, drafting a hassle-free “supports listing” (process batching, quiet hours, written instructional materials) helped me communicate to HR without oversharing her latest blog

  7. Ребятки все пушка https://mos-akpp.ru Добрый вечер помогите купил у снега клад пустой как сапорту написать..? во во так даже бывает…

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>