Firefox 44 for developers

To test the latest developer features of Firefox, install Firefox Developer Edition. Firefox 44 was released on January 26, 2016. This article lists key changes that are useful not only for web developers, but also Firefox and Gecko developers as well as add-on developers.

Changes for Web developers

Developer tools

HTML

CSS

  • position: fixed; now always creates a new stacking context (Firefox bug 1179288).
  • The support of unicode-range has been enabled by default (Firefox bug 1119062).
  • Our experimental implementation of CSS Writing Modes has been updated to reflect the latest specification:
  • The non-standard properties -moz-math-display and -moz-window-shadow are no more available from Web content (Firefox bug 1207002, Firefox bug 1211040, and Firefox bug 1212607).
  • The font-style property now distinguishes between oblique and italic when both variants are available (Firefox bug 543715).
  • Though not supported, the properties marks, orphans, page, size, and widows, were parsed and @supports was incorrectly reporting them as supported; this has been fixed and the properties are not parsed anymore, nor marked as supported (Firefox bug 1215702).
  • The internal value -moz-mac-unified-toolbar has been removed from the possible values for the appearance property (Firefox bug 1206468).
  • Several -webkit prefixed properties and values have been added for web compatibility, behind the preference layout.css.prefixes.webkit, defaulting to false (Firefox bug 837211):
    • -webkit-animation
    • -webkit-animation-delay
    • -webkit-animation-direction
    • -webkit-animation-duration
    • -webkit-animation-fill-mode
    • -webkit-animation-iteration-count
    • -webkit-animation-name
    • -webkit-animation-play-state
    • -webkit-animation-timing-function
    • -webkit-text-size-adjust
    • -webkit-transform
    • -webkit-transform-origin
    • -webkit-transform-style
    • -webkit-transition
    • -webkit-transition-delay
    • -webkit-transition-duration
    • -webkit-transition-property
    • -webkit-transition-timing-function
    • -webkit-border-radius
    • -webkit-border-top-left-radius
    • -webkit-border-top-right-radius
    • -webkit-border-bottom-left-radius
    • -webkit-border-bottom-right-radius
    • -webkit-appearance
    • -webkit-background-clip
    • -webkit-background-origin
    • -webkit-background-size
    • -webkit-border-image
    • -webkit-box-shadow
    • -webkit-box-sizing
    • -webkit-user-select
    • -webkit-linear-gradient() Firefox bug 1210575
    • -webkit-radial-gradient"() Firefox bug 1210575
    • -webkit-repeating-linear-gradient() Firefox bug 1210575
    • -webkit-repeating-radial-gradient() Firefox bug 1210575

JavaScript

New APIs

Changes

Removals

Interfaces/APIs/DOM

DOM & HTML DOM

Canvas

WebGL

IndexedDB

Service Workers

WebRTC

New APIs

Miscellaneous

MathML

No change.

SVG

No change.

Audio/Video

No change.

HTTP

Networking

No change.

Security

Changes for add-on and Mozilla developers

Interfaces

No change.

XUL

No change.

JavaScript code modules

XPCOM

  • The nsIDOMWindow interface is now empty. Its contents were either no longer used, had moved elsewhere, or were only used from C++. The items available from C++ code now reside in the nsPIDOMWindow interface (Firefox bug 1216401).

Other

  • Due to breaking changes in Firefox 44 (bug 1202902), add-ons packed with cfx will not work any longer. To make your add-on compatible again, please use jpm. You can find steps to migrate from cfx to jpm here.

Older versions