Archive for June, 2014

Firebug 2.0.1

Saturday, June 21st, 2014

The Firebug team released Firebug 2.0.1. This version represents maintenance release fixing some reported bugs and updating several locales.


Firebug 2.0.1b1 has also been released to update users on AMO beta channel. This version is exactly the same as 2.0.1


Firebug 2.0.1 is compatible with Firefox 30 – 32

Firebug 2.0.1 fixes 10 issues.


Please post feedback in the newsgroup, thanks.

Jan ‘Honza’ Odvarko


Firebug 2.0

Tuesday, June 10th, 2014

Fresh new Firebug 2 has been released and it’s time to see what new features has been introduced in this version.

  • Firebug 2.0 is compatible with Firefox 30 – 32

Firebug 2.0 beta 8 has also been released to update users on AMO beta channel. This version is exactly the same as 2.0


Firebug is an open source project maintained by developers from around the world and here is a list of all members who contributed to Firebug 2

  • Jan ‘Honza’ Odvarko
  • Sebastian Zartner
  • Simon Lindholm
  • Florent Fayolle
  • Farshid Beheshti
  • Steven Roussey
  • Markus Staab
  • Sören Hentzschel
  • Belakhdar Abdeldjalil
  • Thomas Andersen
  • Jakob Kaltenbrunner
  • David Gomez
  • Leif Dreizler
  • Luca Greco
  • Benediktas Knispelis

There are also plenty of translators who localized Firebug into 35 languages!


Before we jump right into the details, let’s see how the current UI looks like. Firebug 2 went through a face lift in this version. World class designers have been working on the new theme and the user interface is now clean and more intuitive.

Firebug 2 UI:


The screenshot shows Win OS theme other OSes (Linux and Mac) have own custom theme.

New Features

Firebug 2 introduces many new features and bug fixes also because we completely removed dependency on the ancient Firefox debugging engine (aka JSD1) and incorporated new debugging engine known as JSD2.


Syntax Highlighting

One of the most visible new features is probably that the Script panel supports JavaScript syntax highlighting.

Syntax coloring is also there if you edit HTML as a free text by clicking on the Edit button in the toolbar. The same for CSS source edit mode…

Pretty Print

The Script panel also supports pretty-printing and if you deal with minified JavaScript code you’ll find this feature extremely useful.

DOM Events Inspector

Firebug 2 integrates existing EventBug extension and introduces new Events side panel within the existing HTML panel. This panel lists all of the event handlers on the page grouped by event type for the currently selected DOM element. The panel is nicely integrated 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 (read more).

Searching in HTML Panel

Search in the HTML panel has been improved and the user can now use CSS selectors or regular expressions to find specific elements.

Code Auto Completion

Code auto-completion system has been improved across Firebug 2 UI on several places. It’s now available in the Command Editor (within the Console panel) where you can press the <tab> key to open a little completion popup window.

Auto completion works even in breakpoint-condition popup dialog where it offers variables in the current scope.

You can enjoy auto-completion when editing HTML attributes (works for SVG attributes too) and also within HTML style attribute. All these little details make Firebug an awesome tool to use!

JavaScript Expressions Inspector

When debugging and stepping through your code you can quickly inspect and explore details of any JavaScript expression you see in the Script panel. Just hover your mouse over the expression or selected piece of code and see the result in the tooltip.

You can also right click on an expression (or again on the current selection) and pick Use in Command Line or Inspect in DOM Panel actions.

Console Log Grouping

There is new option in the Console panel that allows to group console logs coming in a row from the same location (on by default).

Inspect JavaScript Function Return Value

This feature allows to examine and modify return value of a JavaScript function. See an example:

function myFunction() {
return foo();

The usual problem in other debuggers and tools is is how to examine the return value of foo(). Firebug allows that by stepping through a return statement and displaying the value within the Watch side panel. It even allows you to modify the return value through the Watch panel just like other values (read more).

Show/Hide Firebug Panels

One change we introduced in Firebug 2 is the way how to hide/show individual panels. Check out the next screenshot that depicts how it’s done.

Displaying Original CSS Color Values

Another nice enhancement allows displaying original CSS color values. There is a new option Colors As Authored in the CSS panel that allows displaying CSS color values as they were defined. This makes it easier to compare the styles interpreted by the browser with the ones inside the original CSS source file. While this new option is now the default, you still have the possibility to switch to hexadecimal, RGB or HSL formatting.

Quickly create new HTML attribute

There is a new way how to quickly create new attributes for HTML elements. All you need to do is hover mouse cursor over the closing arrow bracket of an element you want to add a new attribute to. See, the cursor changes its shape into a hand.

Click on the closing tag to open an inline editor and start typing an attribute name.

The rest works as usual. After you typed the name press the tab key and type the attribute value.

Inspect Registered Mutation Observers

The existing getEventListeners() command (see a Firebug tip) has been extended and it now displays also registered mutation observers for given element.

You can use this test page to try it yourself.


See also Firebug 2.0 release notes.


Firebug Extensions

As usual we spent some time testing existing Firebug extensions. Here is a list of those that passed our review and work with Firebug 2.0.

  • AMF Explorer AMF Explorer is based on the JSON Explorer and XML Explorer features of Firebug, AMF Explorer allows web developers to view deserialized AMF messages in Firebug’s Net panel.
  • Console Export Export data from the Console panel
  • CSS Usage See what CSS rules and properties are actually used in your app.
  • Firediff Additional insight into the changes that are being made to the components of the page
  • FireLogger Logging support for web developers (PHP, Python, ColdFusion) (see also this post)
  • FirePath adds a development tool to edit, inspect and generate XPath 1.0 expressions and CSS 3 selectors
  • FirePicker Adds color picker to Firebug’s inline CSS editor. (see also this post)
  • FireQuery Adds a collection of jQuery-related enhancements to Firebug. Recommended for all jQuery developers. (see also this post)
  • FireStorage Plus! Is an extra panel to Firebug for displaying and manipulating the web storage containers such as localStorage and sessionStorage. (see also this post)
  • FlashFirebug Debug ANY AS3 SWF files on the web. Edit properties and inspect elements. Redirect SWF output to the extension. Run AS3 code and transform objects on the fly. Access SWF assets with the decompiler. View AMF calls and Shared Objects and much more!
  • Illuminations for Developers Takes JavaScript frameworks and makes their internals visible inside Firebug, including views, models, class names, and more.
  • Javascript Deminifier Deminify javascript before it is downloaded.
  • NetExport NetExport is a Firebug extension that allows exporting data from the Net panel.
  • Omnibug Omnibug is a plugin for Firebug to ease developing web metrics implementations. Each outgoing request (sent by the browser) is checked for a pattern; if a match occurs, the URL is displayed in a Firebug panel, and decoded to show the details of the request. In addition, requests can be logged to the filesystem.
  • PageSpeed Page Speed is an open-source Firefox/Firebug Add-on. Webmasters and web developers can use Page Speed to evaluate the performance of their web pages and to get suggestions on how to improve them.
  • YSlow YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages. YSlow is also a Firefox add-on integrated with the Firebug web development tool.
  • ZikulaBug ZikulaBug is a Firebug extension, which provides a friendly interface for Zikula’s DebugToolbar. It allows to browse Zikula debug data grouped in eight tabs: General, Configuration, SQL, Templates, Function Executions, Log Console, HTTP request and Settings.
  • Dojo Firebug Extension Support for Dojo based app debugging.
  • Firefinder find HTML elements matching chosen CSS selector(s) or XPath expression quickly.
  • Fireflow Provides method call logs in a tree format.

You can also see the complete list of all extensions.


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You can also post feedback in the newsgroup.


Jan ‘Honza’ Odvarko