0.4 Release Notes

New Features

    JavaScript Debugger

  • There is a new top-level tab for JavaScript debugging
  • Error Console

  • Stack traces are displayed along with JavaScript errors
  • Line numbers are displayed next to XMLHttpRequest spy entries
  • Logging

  • The "printfire" function is no longer supported. It has been replaced by "window.console.log()", which is now available to all web pages.
  • "console.log()" supports printf-like string formatting
  • A whole variety of logging functions options are available. See here for examples.
  • Command Line

  • Command line evaluation now happens in the context of the window, so you can use syntax like "var a = 42;" to set global variables
  • The command line history remembers what you were typing if you hit up and then down again
  • Functions like $() from Prototype are no longer overridden by the FireBug equivalent


  • In the DOM tab, you can expand array objects to show their items
  • In the DOM tab, you can expand function objects to show their source
  • In the DOM tab, long strings are truncated
  • In the DOM tab, you can expand array long strings to show their full value
  • In the Source tab, script, style, and link elements can be expanded to show their source
  • Control-clicking URLs will now open them in a new tab on Windows
  • Element links have a tooltip that shows their XPath


  • When you re-load the page, FireBug will try to re-select the object was selected in the inspector
  • Each browser tab keeps its own FireBug state independent of other browser tabs (whether FireBug is open and which inspector tab is selected)
  • New Firefox windows and tabs always start with FireBug hidden
  • Disabling FireBug will automatically close it
  • Opening FireBug will automatically re-enable it if it was disabled

Bug Fixes

    XMLHttpRequest Spy

  • XMLHttpRequest posts with XML content now display correctly
  • A warning is logged when a synchronous XMLHttpRequest is opened (until I can fix this for real)
  • XMLHttpRequest URLs are once again selectable


  • XML documents documents no longer have their stylesheet stripped away
  • win.__firebug__ error no longer occurs during page load
  • Long paths in the inspector status bar no longer push the inspector tabs off the screen
  • Fixed a bug where an infinite loop of errors would be dumped to the FireBug console

Known Problems

  • The XMLHttpRequest spy won't work on XML documents
  • The XMLHttpRequest spy won't work on synchronous requests
  • The debugger crashes from time to time. I haven't spotted the pattern yet, but scripts compressed using Dean Edwards' packer are particularly sensitive. This seems to be a problem with the Firefox debugging API, and not something I can fix without making C++ changes to Firefox.