Working with a customer, I was explaining the 3 rendering engines that we have in Internet Explorer 8 (Quirks, IE7 Standards, and IE8 Standards), and how you opt into them. As we went through this, a question came up where I didn’t know the answer: what happens if you have a page whose DOCTYPE specifies Quirks mode, but which hosts an IFrame containing a page whose DOCTYPE specifies standards mode? My search engine mojo may have been inadequate that day, but I couldn’t locate an authoritative answer.
Rather than guess, I figured I would build a test. I wrote the following page, and called it guest.html:
Now, let’s host this HTML in an IFrame inside of a page which specifies Quirks Mode:
<html> <head> <title>Mixed rendering test</title> </head> <body> <p>I am the host</p> <iframe src="guest.html"></iframe> </body> </html>
When we run it – what do we find?
So, a standards page inside of an IFrame on a Quirks page still runs in standards. Seeing is believing.