[whatwg] window.onerror and cross-origin scripts

Simon Pieters simonp at opera.com
Wed Sep 21 02:25:34 PDT 2011

On Wed, 21 Sep 2011 08:16:41 +0200, Simon Pieters <simonp at opera.com> wrote:

> On Wed, 21 Sep 2011 05:02:47 +0200, Boris Zbarsky <bzbarsky at mit.edu>  
> wrote:
>> On 9/20/11 5:40 PM, Simon Pieters wrote:
>>> However, it is still possible to tell if the user is logged in or not  
>>> if
>>> a site serves a script for a particular URL when the user is logged in
>>> and redirects to the home page or so when the user is not logged in.
>> Can't you tell this from the load event for the <script> tag, without  
>> involving the error event in any way?
>> I'd love it if we could close this hole up, but the ship has long  
>> sailed.  :(
>>> There are other ways to
>>> tell if the user is logged in, however it seems we should try to keep
>>> them to a minimum.
>> I'm not sure that onerror and onload are really different ways to tell  
>> here.
>> Unless the proposal is that in this case onload fire instead of onerror  
>> for the script that ends up as an HTML document?
> We don't support <script onload> yet. When we implement that, it's  
> likely that we would try to find ways to not leak information in some  
> way (possibly always firing onload for cross-origin scripts if that  
> doesn't break Web sites).

Oops. Bogus testing on my part. We do support <script onload>. Will have  
to investigate whether we should change our behavior for the cross-origin  

Simon Pieters
Opera Software

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