Firefox Developer Edition Notes

Version 39.0a2, first offered to Firefox Developer Edition users on April 3, 2015

Check out "What’s New" and "Known Issues" for this version of Firefox below. As always, you’re encouraged to tell us what you think, or file a bug in Bugzilla. If interested, please see the complete list of changes in this release.

For more information about Developer Edition please see this MDN article and also this hacks.mozilla.org post.

What’s New

  • New

    NPAPI Plug-in performance improved via asynchronous initialization

  • New

    Support for 'switch' role in ARIA 1.1

  • Changed

    Disable use of RC4 except for temporarily whitelisted hosts

  • Changed

    Removed support for insecure SSLv3 for network communications

  • HTML5

    Implement <link rel="preconnect">

  • HTML5

    List-style-type now accepts a string value

  • HTML5

    Vertical text mode enabled by default on Developer Edition

  • HTML5

    Cascading of CSS transitions and animations now matches the current spec

  • HTML5

    Enable the Fetch API by default

  • HTML5

    Implement Cache API

  • HTML5

    Added support for CSS Scroll Snap Points

  • Developer

    Drag and drop enabled for nodes in Inspector markup view

  • Developer

    Webconsole input history persists even after closing the toolbox

  • Developer

    localhost is now available offline for WebSocket connections

  • Developer

    Cubic bezier tooltip now shows a gallery of timing-function presets for use with CSS animations

  • Fixed

    Improve performance for IPv6 fallback to IPv4