W3C home > Mailing lists > Public > www-style@w3.org > November 2007

Re: Proposal of @ua

From: David Woolley <forums@david-woolley.me.uk>
Date: Sat, 24 Nov 2007 12:21:38 +0000
Message-ID: <47481752.1040400@david-woolley.me.uk>
To: www-style@w3.org

Brad Kemper wrote:
> because of some sort of JavaScript incompatibility? OK, so they are 

I am pretty sure that IE was pretending to be Netscape from before 
browsers started supporting scripting.  That was probably to avoid being 
taken for Lynx or Mosaic.

Another, even dodgier reason, is that you assume anything unknown is a 
search engine and feed it a keyword stuffing page, although that 
shouldn't be an issue for CSS.

> anyone who can't understand some CSS I've written end up with 
> overlapping text or button links that are behind some other element as a 

This happens to me a lot even when using IE.  User agent detection won't 
help here because the problem is that sites assume out of the box IE 
(sometimes with other constraints, like fully screen 1024 x 768). 
Simply going to Tools | Options | Accessibility | Ignore author font 
sizes is enough to break many important sites.

> issues that a site might have with Fresco that cannot be dealt with via 
> simple object detection in JavaScript, then how else can the author deal 
> with them without detecting your UA?

Most use of object detection is simply to identify a user agent, not to 
work out specifically what DOM features are available.  It's simply 
another way of browser sniffing.

> Hopefully, over time, more and more will realize the folly of 
> "white-listing" browsers and driving all others away. Since it is 

I've really seen little progress in this direction. Instead, what 
happens is that each major revision of the web site or web application 
results in certain, older, browsers being removed from the supported 
browsers (even if the site doesn't actually do white listing).
> So, given that, most authors that write for non-IE browsers do so by 
> writing rules that any user agent can be assumed to understand. Only 

Authots who want to write for non-IE browsers are in the minority.  They 
may be the most likely ones to use @ua, although I think some of the 
majority might consider providing a very bland style sheet for anything 
other than the latest two versions of IE.

>> How do determine which browsers are the "major browsers" anyway?
>> Can you trust the server's agent log stats given that most browsers are
>> compelled to lie about what they are?
> I trust them well enough. I use what information I have available to 
> me.  I look at my Google Analytics, which I believe does its best to 

I don't know how prevalent user lying is in this respect, but the reason 
that non-IE browsers have configurable user agent strings is to allow 
users to get round white listing.  At least for Lynx, it used to be a 
common question as to what was the best value to put in the user agent 
string to make sites believe you were IE.  There was a feeling that, 
whilst it would have been dishonest, or even illegal, for the out of the 
box version to pretend to be IE, it was perfectly reasonable for end 
users to set it to exactly match IE.  You can probably assume that Lynx 
is seriously underestimated in browser statistics, even if the true 
number is also small.

The most likely result of the production of better browser 
identification libraries is that user agent strings will more precisely 
match those of IE.

> I have to prioritize and concentrate my efforts where I see the most 
> need, and one of the big 3 or 4 that account for 99% of the traffic 

Smaller organisations will often set the threshold at 80 or 90% and 
exclude anything except IE from serious consideration.

David Woolley
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Received on Saturday, 24 November 2007 12:22:01 UTC

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