Will an iframe render in quirks mode?

J

3

11

I'm working on setting up a page and am having difficulty with getting it to look well across browsers (actually just IE, as it renders properly for mozilla and webkit). I'm wanting to rule out quirks mode before seriously considering old IE bugs fixed since IE6. The container page has a declared doctype, however the iframe code does not. Will the iframe content be rendered in quirks-mode (because it does not have a doctype) or standards mode (because the container has a doctype)? The source follows this scheme:

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
...
<body>
...
<iframe ...>
    <html>
    <head>
    ...
    </head>
    <body>
    ....
    </body>
    </html>
</iframe>
...
</body>
</html>

Jess answered 15/9, 2010 at 13:16 Comment(0)

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15

CAVEAT EMPTOR

As some have sadly failed to notice this answer was posted and accepted quite a long time before IE9 existed which changes the terms of the question. I would normally have deleted this to avoid catching any more downvotes but since the answer is actually still true and sadly relevant to a substantial portion of the browser demographics, I'll leave it up. Just please don't downvote it any more.

Quirksmode: IE renders iframes as separate document nodes, doctype is not inherited, and quirks is the default.

Edit: somebody else's demonstration of your problem and proof of non-inheritance (with thanks to my bookmarks :P )

However, you've chosen "Almost" as your doctype which means iframes aren't allowed anyway. The only way you could get valid iframes is if the parent was in quirks which makes inheritance or not a moot point.

Recommended reading.

Suspiration answered 15/9, 2010 at 13:58 Comment(3)

Wrong - as of IE9, doctype IS inherited... your confusion stems from the fact that in IE8, this is different... – Randolph 6/9, 2012 at 7:47

Agree with Quandary. I have the same issue with IE10. The parent doctype is propagating down to the IFrame regardless of what is specified in that page (that page renders different when it's opened on it's own). – Cartel 18/10, 2012 at 23:27

My "confusion" comes from the fact that the answer predates IE9 by many months. The helpful thing to do would have been to edit accordingly, but hey I guess downvotes are fun and easy, and reading is tech. – Suspiration 3/6, 2013 at 14:40

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23

Prior to IE9, the webpage within the iframe would render according to its own doctype, not according to the doctype of the parent container. However, in IE9, Microsoft changed the behavior so that the child iframe inherits its doctype/rendering from the parent container.

Note that IE9 will still behave in the traditional manner (iframe honors its own doctype) whenever compatibility view is used.

The best workaround for folks in your situation--writing a standards compliant container page but needing to include an iframe with a quirks mode page--is to add either of the following meta tags between your doctype and the opening tag in the parent page.

<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7">
<meta http-equiv="X-UA-Compatible" content="IE=8" />

These tags will essentially tell IE9 to pretend it is IE7 or IE8. Including in the emulation is the logic used to determine rendering mode for the child iframe. The downside of this workaround is that you will not be able to use any of the new features supported by IE9 in your parent page, but that is probably preferable to massive rendering errors in the child page.

See http://web.archive.org/web/20110905060718/http://www.sitepoint.com/forums/html-xhtml-52/ie9-iframes-doctypes-you-743000.html for more information.

Madsen answered 11/4, 2011 at 16:22 Comment(7)

is there any other slution that enable executing parent IE9 standards mode Frame along with quirks or EmulateIE7 child iframe? – Emulous 30/7, 2012 at 15:20

@mikepr: Preferable ? No, it isn't. Fact is, you shouldn't produce HTML with quirks mode - ever. Some important MS products do btw, with no workaround... – Randolph 5/9, 2012 at 8:33

Oh and by the way: Stop upvoting this, it sounds good, but it doesn't work. – Randolph 6/9, 2012 at 7:45

While I agree that this does not work in all situations, it does reduce some of the issues and does deserve to be upvoted. Unfortunately you sometimes cannot control what is contained within your iframe and therefore cannot control if it's standards compliant. I've personally had an issue where this solution resolved the problem, at least temporarily until the other app could be updated to be standards compliant. – Nestling 9/1, 2013 at 13:26

@mikepr: No, unfortunately, it is not preferable. – Randolph 23/1, 2013 at 10:53

What if you are using IE9, the parent page you're viewing is quirks-mode, and the iframe has a doctype and specifies IE=Edge compatibility? – Amicable 3/5, 2013 at 20:38

external link broken unfortunately – Autography 22/5, 2015 at 10:51

S

15

CAVEAT EMPTOR

As some have sadly failed to notice this answer was posted and accepted quite a long time before IE9 existed which changes the terms of the question. I would normally have deleted this to avoid catching any more downvotes but since the answer is actually still true and sadly relevant to a substantial portion of the browser demographics, I'll leave it up. Just please don't downvote it any more.

Quirksmode: IE renders iframes as separate document nodes, doctype is not inherited, and quirks is the default.

Edit: somebody else's demonstration of your problem and proof of non-inheritance (with thanks to my bookmarks :P )

However, you've chosen "Almost" as your doctype which means iframes aren't allowed anyway. The only way you could get valid iframes is if the parent was in quirks which makes inheritance or not a moot point.

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