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Firefox 24 for developers

Want to help document Firefox 24? See the list of bugs that need to be written about and pitch in!

Changes for Web developers


  • The two values -moz-zoom-in and -moz-zoom-out of the cursor property have been unprefixed to zoom-in and zoom-out (bug 772153).


  • The <track> element has been implemented behind the media.webvtt.enabled property (bug 833385).



Developer Tools

  • The Network inspector now lets you filter by content type (CSS/image/font etc.) and see the relevant size and load times.
  • The Devtools options panel to the left lets you disable/enable Javascript temporarily.
  • Extension developers may use the new Browser Console for Chrome-level scripts (Replaces Error Console).


  • The dir attribute for controlling directionality of formulas on e.g. <math> or <mrow> elements is now equivalent to using the direction CSS property.
  • The equal sign ("=") is now stretchable.
  • The "updiagonalarrow" value for the notation attribute on <menclose> elements has been added.

See also

Older versions

Document Tags and Contributors

 Last updated by: teoli,