[whatwg] Javascript: URLs as element attributes

Philip Jägenstedt philipj at opera.com
Thu Dec 2 00:32:43 PST 2010

On Wed, 01 Dec 2010 16:24:31 +0100, Boris Zbarsky <bzbarsky at mit.edu> wrote:

> On 12/1/10 3:16 AM, Philip Jägenstedt wrote:
>> Do you do that just for inlines, or also when navigating to javascript:
>> URLs? If it's both, then that's something we'd need to standardize,
>> unless all browsers already do the same.
> It's both in Gecko.  We really do try to keep the number of  
> special-cases to a minimum.  ;)

I'm looking forward to some standardization effort on this point.

> I agree that we probably need to standardize this, because I fully  
> expect web sites to depend on the ISO-8859-1 bit when all the charcodes  
> are < 255.
>> Indeed, so the question is just what the compat constraints are.
> Well, no.  There's the question of what's least confusing for authors  
> too; see my other mail about that in this thread.

This one?

On Tue, 30 Nov 2010 20:32:06 +0100, Boris Zbarsky <bzbarsky at mit.edu> wrote:

> One other thing.... since this is a generic protocol, if we define  
> special-case behavior for it in some cases (e.g. <img>), that opens up  
> some cans of worms.  For example, what should url("javascript:") do in  
> CSS?  HTML5 seems like the wrong place to define that....

On this point I can only say that I think that javascript: in CSS should  
also not execute, and doesn't in Opera (before or after my changes).

>> Right, these aren't inlines, in Opera terminology at least. As far as I
>> can see the spec agrees on this, as frames/iframes have their own
>> browsing contexts.
> So do <object>s, sometimes, right?

Yes, but as far as I can tell from the algorithm [1], the browsing context  
isn't created until step 8, after the URL in data="" has been resolved and  
fetched. In other words, at the time the steps for handling javascript:  
[2] are run, there's no browsing context, and it will be treated as any  
other inline. This is a good thing IMO, as it would be quite confusing if  
the context in which the script executed depended on the expected type of  
the <object> content.

The spec change that I'm suggesting is to remove the case "If the Document  
object of the element, attribute, or style sheet from which the  
javascript: URL was reached has an associated browsing context", which  
would mean (among other things) that <object data="javscript:..."> would  
never execute. But again, let's wait a little bit longer and see if any  
compat issues arise.


Philip Jägenstedt
Core Developer
Opera Software

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