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Re: [File API] Issue 182 about OperationNotAllowed

From: Ian Hickson <ian@hixie.ch>
Date: Tue, 4 Oct 2011 01:00:13 +0000 (UTC)
To: Jonas Sicking <jonas@sicking.cc>
cc: Arun Ranganathan <arun@mozilla.com>, Anne van Kesteren <annevk@opera.com>, public-webapps <public-webapps@w3.org>
Message-ID: <Pine.LNX.4.64.1110040055160.20981@ps20323.dreamhostps.com>
On Mon, 3 Oct 2011, Jonas Sicking wrote:
> 
> I looked at how for example WebSockets and EventSource exposes error 
> information. I would have thought in both cases that it would have been 
> done as a property on the websocket/eventsource object itself. However I 
> couldn't find any such property, and since the "error" events fired by 
> both specifications are simple Events it doesn't appear as if the 
> information is exposed on the event object either.
> 
> Do neither of these specifications make error information available?

Web Sockets exposes error information in the 'close' handler, if that 
counts. That's unrelated to exceptions, though. It uses a custom event 
interface type.

Generally speaking I try to avoid exposing too much error information to 
script (as opposed to the developer console) because it can often lead to 
security problems (e.g. leaking information about intranet topology).

HTMLMediaElement exposes error state on a .error attribute that returns a 
MediaError object (or null), which itself just has a single .code 
attribute currently, that being a value from 1 to 4 (corresponding to some 
defined constants). At some point in the future it may be extended to 
provide more information in the object, but there are no immediate plans 
to do so. In any case, this is also not an exception, and no attempt is 
made to keep these codes synced with the exception codes.

All exception handling in the HTML spec uses the DOM Core behaviour.

HTH,
-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Tuesday, 4 October 2011 01:03:28 GMT

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