Thursday, March 27th, 2008

Where is Firefox on Acid 3? Here.

Category: Browsers, JavaScript, Standards

Some people have been surprised to not hear much from Mozilla around Acid 3. WebKit and Opera are duking it out, but what about Firefox?

Mike Shaver of Mozilla has posted on his views that Acid 3 is a missed opportunity and is pretty damning of the whole thing:

Ian’s Acid 3, unlike its predecessors, is not about establishing a baseline of useful web capabilities. It’s quite explicitly about making browser developers jump — Ian specifically sought out tests that were broken in WebKit, Opera, and Gecko, perhaps out of a twisted attempt at fairness. But the Acid tests shouldn’t be fair to browsers, they should be fair to the web; they should be based on how good the web will be as a platform if all browsers conform, not about how far any given browser has to stretch to get there.

The selection of specifications is also troubling. First, there is a limitation that the specification had to be suitably finished by 2004, meaning that only standards that were finalized during the darkest period of web stagnation were eligible: standards that predate people actively reviving the web platform, through work like the WHATWG’s <canvas> specification. While this did protect us from tests requiring the worst of SVG’s excesses (1.2, with support for such key graphical capabilities as file upload and sockets, was promoted to CR in 2007), it also means that it includes @font-face, a specification which was so poorly thought of that it was removed in 2.1. I can think of no reason to place such time-based restrictions on specification selection other than perhaps to ensure that there has been time for errata to surface — but in the case of CSS, those errata are directly excluded! Similarly, the WHATWG’s work to finally develop an interoperable specification for such widely-used things as .innerHtml were excluded.

Mike also highlighted a couple of things of note:

“Due to late changes in the Cross Site XMLHttpRequest specification which made our implementation incomplete, it was decided to remove support for this technology rather than include only partial support.”

It seems that there is flux in the spec around cookies, so Firefox 3 won’t have cross domain XHR which is a disappointment. I really hope that the spec is finalized and we can get this out in browsers ASAP.

Mike points to John Resigs compatibility regression coming out due to code like:


  1. if (!document.getElementsByClassName)
  2.   document.getElementsByClassName = function(instanceMethods){
  3.     // ...
  4.   };

The JavaScript implementations don’t seem to be implementing the spec (often because they implemented the method before there was ever a spec!!!), so now with browsers coming online with implementations, they are different. The libraries cannot return a live nodelist, and some of them add on magic to the nodes that are returned, which the browser implementations do not.

Posted by Dion Almaer at 7:32 am

3.4 rating from 40 votes


Comments feed TrackBack URI

I think a ‘we are too late in the dev cycle for Firefox 3 to push through compliance for Acid3’ would have been sufficient. Developers understand you can’t make large changes to the underlying infrastructure this late in the game.

Comment by tj111 — March 27, 2008

It does seem a little standoffish doesn’t? They’re constantly making changes to their software, just the same as Safari and Opera. If they’re currently focusing their changes on support for HTML5 then that’s cool with me, I’m pretty sure I’m not using anything in my code that is affected by the failure of the Acid test. They should just say that compliance of the test is in the books and leave it with that

Comment by starkraving — March 27, 2008

I love how he’s telling Ian Hixie that Acid 3 doesn’t have enough HTML 5 stuff in it…. when Ian is the one that is leading the HTML 5 effort! Ian just realized that Acid 3 was focused on a different baseline of browser features and it wasn’t appropriate to put HTML 5 stuff in that at this time.


Comment by BradNeuberg — March 27, 2008

I couldn’t agree more with the sentiments. The whole ACID 3 race reminds me of the lengths video card companies in the 90s went to, tweaking their cards to score impressive results on artificial benchmarks. The order in which browsers have “successfully” achieved ACID 3 compliance is the exact opposite order you can count on them to successfully render a website.

Comment by JonathanLeech — March 28, 2008

“The order in which browsers have “successfully” achieved ACID 3 compliance is the exact opposite order you can count on them to successfully render a website.”

Really? My experience has been that, except in cases of targeting specific browser bugs, Safari is generally equivalent to Firefox or better in terms of “reliable” rendering.

Comment by Trevor — March 30, 2008

@JonathanLeech: Have you any clue what you just said?

Comment by Carbon43 — March 31, 2008

Leave a comment

You must be logged in to post a comment.