Aurora 12 is out – improvements and updated Developer Tools

Aurora 12 is out, together with updated Developer Tools, and these are the improvements/changes.


A few of the improvements that stand out a little more:

ECMAScript Harmony’s Simple Map and Set builtins

For testing purposes, we have implemented ECMAScript Harmony’s Simple Map and Set builtins. This is only in Aurora and will be disabled when it goes to beta, so please test it out now and give feedback! There is also MDN documentation on Set and MDN documentation on Map if you want to learn more.

If you are more interested in Harmony progress, read up on our implementation work for ECMAScript 6

Support multitouch on Android

We’re happy to now have implemented multitouch for Firefox on Android!

Let authors put line breaks (newlines) in tooltips (title attribute)

It might seem like a small thing, but has been discussed quite some time. You can now use newlines for tooltips!

XMLHttpRequest should allow you to specify a network timeout in ms (for async requests)

Instead of timeouts and similar, this offers a way to specify a network timeout for XMLHttpRequests using the timeout attribute.

List of improvements

Here are all the improvements we’ve made complete with links to each bug listing for those who want to read up more on respective implementation.







Developer Tools

There has been a total of 89 improvements to Web Console, Scratchpad, Style Editor, Page Inspector, Style Inspector, HTML view and Page Inspector 3D view (Tilt). Here are the highlights:

About Robert Nyman [Editor emeritus]

Technical Evangelist & Editor of Mozilla Hacks. Gives talks & blogs about HTML5, JavaScript & the Open Web. Robert is a strong believer in HTML5 and the Open Web and has been working since 1999 with Front End development for the web - in Sweden and in New York City. He regularly also blogs at and loves to travel and meet people.

More articles by Robert Nyman [Editor emeritus]…


  1. dr.pradhan

    Please let me know as to how might I enable automatic updates.Thanks,

    April 25th, 2012 at 02:51

    1. Janet Swisher

      Automating updating is turned on by default. See the Support Knowledgebase for How to configure update options.

      April 25th, 2012 at 11:36

  2. GrampaJerry

    It’s nice to see that Firefox is catching up to Chrome. It’s now only about 1-2 seconds slower than Chrome when starting. I’m still very frustrated that Firefox does not support the HTML5 element or the CSS3 style transform:rotate(). It creates problems for pages I’ve created.

    April 25th, 2012 at 07:43

    1. Robert Nyman

      CSS rotation has been in firefox since version 3.6: CSS transform. Not sure when the Details element will be supported.

      April 25th, 2012 at 15:28

  3. GrampaJerry

    Correction: The HTML5 element I typed did not show up from my original post. It should be DETAILS.

    April 25th, 2012 at 07:46

  4. Jan

    View Source in Firefox 12 is enriched with line numbers. But despite this new richness View Source is worth nothing because it shows less source.
    PHP changes to the HTML of a page are not visible in View Source. In Firefox 12 View Source only shows the initial HTML of the page. The downgrade installs without warning about this issue. I reverted to Firefox 11, and turned off automatic updates.
    To my surprise the actual version of Chrome also seems to think that less is more.
    (I can’t believe this is only on my Mac. And I couldn’t quickly find a way to communicate the issue to Mozilla.)

    April 26th, 2012 at 14:49

    1. Jean-Yves Perrier

      There are no such things as PHP changes to the HTML. PHP generates HTML and the server send it to the browser. What is displayed in the View source is what is sent to the browser, so after PHP generation.

      (In a slightly different way, JavaScript never changes the source of a page, but its DOM structure. View source doesn’t display the DOM structure but the unmodified source).

      April 26th, 2012 at 15:52

      1. Jan

        Well alright, I just tried to find words to express what happens, or what’s not happening.

        What is displayed in View Source in Fx 12, after the page is updated with new HTML, is old HTML. (The actual version of Chrome does this too, the actual versions of Opera and Safari show the new HTML in View Sours, as with Fx before version 12. All of this on a Mac with Snow Leopard.)

        In case I’m not clearly wording the case yet, you might want to take a look a the site we’re setting up After clicking one of the first two categories, the HTML in View Source, is still the HTML of the white start page, the category items are not displayed in View Source’s HTML.

        April 27th, 2012 at 03:27

        1. Will Peavy

          @Jan – you can use Firebug to see DOM manipulations in real-time.

          May 11th, 2012 at 13:39

  5. Alex


    When you View Source on the page, you are seeing the originally rendered HTML from the initial page load. On your site, you are replacing the contents of the page via AJAX after page load, which is Javascript manipulating the DOM. Those changes will never be seen in View Source as explained in Jean-Yves’ comment. If you want to see the modified page source, use a tool like Firefox’s Developer Tools or Firebug to look at the DOM structure.

    May 2nd, 2012 at 11:43

    1. Jan


      I haven’t learned this in school, so my wording may not be very professional, my apologies.

      The initial page is reloaded with new HTML generated by PHP. And in Fx 12 what View Source shows is the old HTML of the initial page. In Fx previous to version 12 View Source shows the new HTML.
      I don’t think it is JavaScript modifying the DOM when you use PHP $_GET.

      Take a look at the page with Fx 11 or the actual Safari browser and you’ll see the changes you think never will be seen in View Source.

      Of course I can (and do) use Firebug, but I like the quick look in the clean View Source to see if my HTML is formatted as nicely as I intended.

      May 3rd, 2012 at 07:26

  6. Michael Hall

    @jan, just in case it is not clear, PHP is processed by the web server and outputs plain old html so you won’t see any of the original php code after the page loads in the browser. javascript on the other hand doesn’t actually change the source code so you will see the original javascript if you view the source of the page after the browser loads it, but javascript can change the structure(DOM) of the page but you won’t see the change by viewing the source since it doesn’t change the original source code, but as suggested using a web dev tool like firebug in firefox or similiar in chrome allows you to see the live source code including the changes made by javascript. (and as far as i know javascript and php works this way on all browsers).

    May 3rd, 2012 at 05:23

    1. Jan


      Just in case it is not clear, take a look at the page to see it happen.

      As I wrote to Alex, my apologies if my wording is not very clear.

      After the initial page is reloaded with PHP processed plain old HTML, in Fx 12 View Source all I see is the same plain old HTML of the initial page. In Fx previous to version 12 I see the new HTML.
      If you want to compare: the actual version of Safari shows the new HTML like old Fx. The actual version of Chrome acts like Fx 12 and also show the old HTML.

      I’m not talking JavaScript changing the DOM, it’s done through PHP $_GET.

      May 3rd, 2012 at 07:31

      1. James

        Sorry Jan, PHP is a server technology and firefox is a client technology, look up client/server architecture in a book, this is how the internet works.

        July 12th, 2012 at 03:52

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