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).
CSS
- 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 of1.0
(bug 349259). - The
line-height
property now also affectstype=button
, with no restrictions (bug 697451). - Change to keyframes' name does not affect current elements (bug 978648).
HTML
No change.
JavaScript
- New ES2015-compatible array comprehensions
[for (item of iterable) item]
and generator comprehensions(for (item of iterable) item)
have been implemented (bug 979865). - Typed arrays are now extensible and support new named properties (bug 695438).
- The
Error.prototype.stack
property now contains column numbers (bug 762556) and has been improved when usingFunction()
andeval()
calls. This can help you to better debug minified or generated JavaScript code. - The
Promise.cast()
method has been renamed toPromise.resolve()
(bug 966348).
Interfaces/APIs/DOM
Navigator.sendBeacon
has been implemented, easing telemetry collection (bug 936340).- Added a
relList
property returning aDOMTokenList
toHTMLLinkElement
,HTMLAreaElement
andHTMLAnchorElement
(bug 968637). - As per the latest specification, the first argument of
OscillatorNode.start
andOscillatorNode.stop
is now optional and defaults to0
(bug 982541). - The method
Navigator.requestWakeLock()
and the non-standardMozWakeLock
are no longer available from the Web on Desktop (bug 963366). - The
DOM_VK_ENTER
constant has been removed fromKeyboardEvent
(bug 969247). - Web components'
Document.register
has been adapted to follow the behavior described in the latest version of the specification (bug 856140). - Basic support for Hit regions on canvas has been added: the methods
CanvasRenderingContext2D.addHitRegion()
andCanvasRenderingContext2D.removeHitRegion()
have been added. These are disabled by default; to activate them set the preferencecanvas.hitregions.enabled
totrue
. (bug 966591) - The non-standard, and deprecated since Firefox 15,
Blob.mozSlice
is no longer supported (bug 961804). - The non-standard
ArchiveReader
andArchiveRequest
are no longer exposed to the Web (bug 968883). - WebIDL constructors cannot be called as functions anymore. They need to be preceded by the keyword
new
. (bug 916644) - Added support for a new value (
alpha
) for the second, optional, parameter of theHTMLCanvasElement.getContext()
method allowing to define if alpha blending must be stored or not for this context. When not, the per-pixel alpha value in this store is always1.0
. This allows the back-end to implement a fast-track. (bug 982480) GlobalWorkerScope.consle
now returns for the regularConsole
;WorkerConsole
has been removed (bug 965860).- The
WebGL_debug_shaders
WebGL extension has been implemented (bug 968374).
MathML
No change.
SVG
<feDropShadow>
, and its interfaceSVGFEDropShadowElement
, from the Filter Effects Module are now supported (bug 964200).
Audio/Video
- On Linux, Gstreamer 1.0 is now supported (instead of 0.10) (bug 806917).
Security
No change.
Changes for add-on and Mozilla developers
- The interface
nsIDOMWindowUtils
now supports the Boolean attributeaudioMuted
andaudioVolume
, 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)
See also
Older versions
- Firefox 29 for developers
- Firefox 28 for developers
- Firefox 27 for developers
- Firefox 26 for developers
- Firefox 25 for developers
- Firefox 24 for developers
- Firefox 23 for developers
- Firefox 22 for developers
- Firefox 21 for developers
- Firefox 20 for developers
- Firefox 19 for developers
- Firefox 18 for developers
- Firefox 17 for developers
- Firefox 16 for developers
- Firefox 15 for developers
- Firefox 14 for developers
- Firefox 13 for developers
- Firefox 12 for developers
- Firefox 11 for developers
- Firefox 10 for developers
- Firefox 9 for developers
- Firefox 8 for developers
- Firefox 7 for developers
- Firefox 6 for developers
- Firefox 5 for developers
- Firefox 4 for developers
- Firefox 3.6 for developers
- Firefox 3.5 for developers
- Firefox 3 for developers
- Firefox 2 for developers
- Firefox 1.5 for developers
Document Tags and Contributors
Tags:
Contributors to this page:
Sebastianz,
kdex,
fscholz,
kohei.yoshino,
teoli,
Nevallem,
rubo77,
Delapouite,
Brettz9,
yisi,
Yarg,
mnoorenberghe,
Ms2ger
Last updated by:
Sebastianz,