Firefox 30 for developers

Changes for Web developers

Developer Tools

  • A Box Model Highlighter has been implemented (bug 663778).
  • Anywhere a DOM node appears in the console output, it is highlighted when you hover over that console output (bug 757866). Similarly all JS functions and objects are highlighted in the console output (bug 584733). More information about the console improvement can be found in this blog post.
  • Support for console.count() has been added (bug 922208).


  • The property background-blend-mode has been enabled by default (bug 970600).
  • The non-standard overflow-clip-box property has been implemented for use in UA stylesheets only (bug 966992).
  • The line-height property now affects single-line text inputs (<input type=text|password|email|search|tel|url|unknown> types) although it cannot shrink them below a line height of 1.0 (bug 349259).
  • The line-height property now also affects type=button, with no restrictions (bug 697451).
  • Change to keyframes' name does not affect current elements (bug 978648).
  • positioned internal table elements not abs pos containing block(relative position for table rows) (bug 63895).


No change.




No change.



  • On Linux, Gstreamer 1.0 is now supported (instead of 0.10) (bug 806917).


No change.

Changes for add-on and Mozilla developers

  • The interface nsIDOMWindowUtils now supports the Boolean attribute audioMuted and audioVolume, a float in the range [0.0 , 1.0], allowing to control the sound produced by a window (that is any tab or iframe). There is no UI for this, but is available to add-ons. (bug 923247)

Older versions