Archive for May, 2014

Firebug 2.0 beta 8

Friday, May 30th, 2014 has Firebug 2.0 beta 8

Firebug 2.0b8 fixes 13 issues
Firebug 2.0b8 is compatible with Firefox 30-32

Beta releases are also uploaded on AMO.


We are releasing the last Firebug 2 beta version today. The final release will be available on Tuesday 10th of June. We need a time buffer to make sure that Firebug 2 xpi bundle has enough time to go through review on AMO.


Let’s check out what’s new in this release.

Pretty Print Button

This is a little change that we introduced to make sure that the support for source code prettifying is more visible to the user. There is a new button on the Script panel toolbar now (issue 7305).

Script Expression Inspection

We already mentioned support for object inspection in the Script panel in the previous post and we introduced some more improvements.

It’s now possible to inspect even selected expressions (issue 7475).

See, the little tooltip says that the result of 10 + 20 is 30. You can also right click on the selection and pick Inspect in DOM Panel or Use in Command Line (both actions will be applied on the selected expression result).


We have also improved the way how expressions under the cursor are analyzed and so for instance, the cases like the following also work as expected (issue 7484).

Check out various position of the mouse cursor and the expression under it.


Please post feedback in the newsgroup, thanks.

Jan ‘Honza’ Odvarko


Firebug 2.0 beta 7

Friday, May 23rd, 2014 has Firebug 2.0 beta 7

Firebug 2.0b7 fixes 8 issues
Firebug 2.0b7 is compatible with Firefox 30-32

Beta releases are also uploaded on AMO.


It’s Friday and another Firebug 2 beta release is available for testing. We are sprinting towards the Final release and counting, 18 days remaining…


Let’s see what other new stuff has been introduced in Firebug 2.

Console Log Grouping

This is one of the nifty little features that make Firebug great tool for development. Grouping of console logs has been available for long time, but the number of logs in a group was displayed on the far right side and not much noticeable. We moved it to the beginning to make it more obvious. See the screenshot.

Script Objects Inspection

This feature has been in Firebug for some time, but we made it working properly now in Firebug 2.

You can right-click on any object directly in the Script panel and pick Inspect in DOM Panel (to continue inspection of the object in the DOM panel) or Use in Command Line (to use object in an expression on the Command Line).

See couple of screenshots.



This allows quick object inspection without necessity to search for them in the DOM main (or side) panel.


Please post feedback in the newsgroup, thanks.

Jan ‘Honza’ Odvarko


Firebug 2.0 beta 6

Friday, May 16th, 2014 has Firebug 2.0 beta 6

Firebug 2.0b6 fixes 6 issues
Firebug 2.0b6 is compatible with Firefox 30-32

Beta releases are also uploaded on AMO.


Let’s see what is new in this release!


DOM Events Inspector

This release integrates the existing EventBug extension and introduces a new Events side panel. This side panel is available in the HTML panel and lists all of the event handlers on the page grouped by event type for the currently selected DOM element. The panel also nicely integrates with other Firebug panels and allows to quickly find out, which HTML element is associated with specific event listener or see the JavaScript source code (issue 5440).


EventBug extension doesn’t support Firebug 2 and you should uninstall it if using this version of Firebug.


Events Side panel


The previous screenshot demonstrates a situation where a <button> element is selected and we can see that two listeners are registered for it: onclick and onmousemove. Name of the handler (in green) is a link that navigates you directly at the right line in the Script panel where you can inspect the JS code.

There is also a section Other listeners for: Window that shows one handler for load event. There is no way to select the window object itself in the HTML panel and so this section is visible all the time (in case any listeners are actually available).

Online example


You can also disable an existing event listener (the same way a CSS properties can be disabled in the CSS panel).


Event Targets

The Events panel displays also event handlers for all targets (parent elements) used when event bubbles.

Imagine the following scenario:

<div id="div1" onclick="onClickDiv1()">
  <div id="div2" onclick="onClickDiv2()">
    <div id="div3" onclick="onClickDiv3()">Click Me!</div>

If the user clicks on div3 element the event will bubble up through the parent elements.

If you select div3 element in the HTML panel the Events side panel shows shows all three listeners (coming from the event targets chain).


  • The top section shows onclick for div3 (the selected element)
  • There are other two sections showing listeners for div2 and div1 elements

Online example


Event Handlers Names

Name of the event handler displayed in the Events panel depends on the way how the event is registered. If it’s an inline event (created within an HTML attribute) the name always corresponds to the attribute (event type) since generated automatically by the browser. If you use addEventListener, the name will correspond to the function passed in.

See an example:

Online example


Wrapped Event Handlers

Some JS libraries (e.g. jQuery) are wrapping the original function into another function. This happens for all registered event handlers, and so searching for the original function might be hard since the link offered in the Events panel always points to the wrapper function coming from particular JS library. But don’t worry, Firebug solves this problem by showing even the original wrapped function.


Online example


Please post feedback in the newsgroup, thanks.

Jan ‘Honza’ Odvarko


Firebug 2.0 beta 5

Friday, May 9th, 2014 has Firebug 2.0 beta 5

Firebug 2.0b5 fixes 7 issues
Firebug 2.0b5 is compatible with Firefox 30-32

Beta releases are also uploaded on AMO.


We made a few UI enhancements and fixed several reported bugs in this release. As usual we have also created more automated tests to ensure stability and avoid regressions.


Show/hide Command Editor

Another change we have introduced in Firebug 2 is related to the way how the Command Editor (aka multiline command line) is opened and closed.

The Command Editor (together with the Command Line) is one of the most useful features for development. It allows the execution of JavaScript code snippets, as well as calling existing functions on the page or defining new ones.

The script is executed in the context of the current page and if the debugger is currently halted (e.g. at a breakpoint), the script is executed in the current debugging frame. So for example you can also use local variables available in the current frame scope in your script.

The following screenshot shows how the Command Editor looks like when opened in the Console panel.


The Command Editor can be opened/closed using the little arrow button in the top right corner, which is exactly the same way how side panels on other panels are opened/closed. This new approach makes the entire UX more consistent.


See the next screenshot showing how the UI looks like if the Command Editor is closed.


You can use the top-right button to open the Command Editor again, or click the bottom-right red button. We kept the red button in there, since it was in Firebug for a long time and users could miss it. But we’d like to remove it at some point since we believe it isn’t that important anymore. What do you think?


Please post feedback in the newsgroup, thanks.

Jan ‘Honza’ Odvarko


Firebug 2.0 beta 4

Friday, May 2nd, 2014 has Firebug 2.0 beta 4

Firebug 2.0b4 fixes 12 issues
Firebug 2.0b4 is compatible with Firefox 30-32

Beta releases are also uploaded on AMO


Let’s see what’s new.


Console API available in Web Workers

This is great news for everyone who’s using web workers and debugging them. The console object and all its API can be now used from within web worker thread as well (issue 2154).


Support for Australis

Firebug 2 user interface has been improved a lot and we paid an extra focus on visual compatibility with the new Australis design introduced in Firefox 29 this week. It’s not only tweaking the design bits, so it looks good and native across different OSes, but also supporting the new Australis UX.

First let’s look how Firebug 2 looks on different platforms (in this order: Mac, Linux, Win).




Australis introduces a new panel menu icon in the upper right corner and new way how to customize this menu. Firebug supports all the new UI/UX.

If you click the new menu toolbar button you should see a panel with Developer icon.

After you click the icon you’ll see a submenu with existing native tools and Firebug at the top (issue 7415).

Customization of the menu is done through a button that is located at the bottom of the menu panel. After you click it, you can drag-and-drop the Firebug icon anywhere you want. Note that Firebug icon is located in the toolbar by default just like always (auto customization done after installation).


So, give it a try and install Firebug 2.0 beta 4


Please post feedback in the newsgroup, thanks.

Jan ‘Honza’ Odvarko