Firefox 29 for developers
Firefox 29 was released on April 29, 2014. 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
Major changes include:
- Vastly improved web console - Arrays are shown inline without clicking to bring up in the right inspector, window objects show their URL, etc.
- Added the console API to Web Workers (bug 620935). Now you can log messages to the Web Console from Web Workers.
- The Network Monitor tool now shows performance statistics using pie charts (Firefox bug 846601).
- On the Inspector, preview tooltips of CSS transforms are now available (Firefox bug 726427).
- DOM elements seen in the debugger and console can be removed or inspected directly, via the new buttons to the right of the variable listing.
- A CSS source map is now supported by the Style Editor (Firefox bug 926014).
- Autocompletion of CSS properties and values has been added to the Style Editor (Firefox bug 717369).
See the Mozilla Hacks blog post for details and other smaller changes.
CSS
- CSS variables have been implemented (Firefox bug 773296). Mozilla Hacks article can be found here. They are enabled by default only for non-release builds (on release builds flip the pref
layout.css.variables.enabled
totrue
if you want to play with them). - Flexboxes now support
visibility
: collapse
(Firefox bug 783470). - The
box-sizing
property has been unprefixed (Firefox bug 243412). - The
will-change
property, a hint to that something will animate has been added. The preferencelayout.css.will-change.enabled
must be switched totrue
to enable it. (Firefox bug 940842) - Scientific exponential notation, like
3e1
or10e+0
, is now supported for<number>
values and derivatives, like<percentage>
and unit values, but not<integer>
(Firefox bug 964529). - Images of type
<gradient>
are now supported inborder-image
(Firefox bug 709587). - The
touch-action
property has been implemented. It is not activated by default; thelayout.css.touch_action.enabled
pref controls it. (Firefox bug 795567) - Remove redundant default style for <pre> element from quirk.css (Firefox bug 948914).
- CSS Variables fallback incorrectly implemented (primary cycles) (Firefox bug 950497).
- @supports conditions with tokens after a declaration's priority should evaluate to false (Firefox bug 909170).
HTML
<input type=color>
and<input type=number>
are available by default.- Support for the non standard
<pre cols>
has been removed, as well as the layout effect of<pre wrap>
. Both effects can, and should, be achieved using CSS. (Firefox bug 949879)
JavaScript
- New ECMAScript 2015 String methods:
String.prototype.codePointAt()
andString.prototype.fromCodePoint()
have been implemented (Firefox bug 918879). - The ECMAScript Internationalization API (ECMA-402) has been implemented and is now enabled by default in Firefox Desktop (Firefox bug 853301):
- To match the updated ECMAScript 2015 draft specification, the
Map
andSet
objects now treat-0
and+0
as the same when checking for key and value equality. Promise
has been enabled by default (Firefox bug 918806).- Completed generators now return an
IteratorResult
object instead of throwing (Firefox bug 958951). - A malformed JSON string parsed by
JSON.parse()
now yields a more detailed error message containing the line and column number that caused the parsing error. This is useful when debugging large JSON data. - The
ArrayBuffer.isView()
method has been added (Firefox bug 896105).
Interfaces/APIs/DOM
- A new type of workers,
SharedWorker
, is now available by default (Firefox bug 924089). - The
URL
interface now supports thesearchParams
property returning aURLSearchParams
object, allowing to modify the search params of a URL (Firefox bug 887836). TheURLSearchParams()
constructor allows easier parsing of query strings. - The
navigator.onLine
property is now supported onWorkerNavigator
, allowing to know the online/offline status in workers (Firefox bug 925437). - As part of the implementation of Web Components, the
HTMLShadowElement
interface has been implemented behind thedom.webcomponents.enabled
. Flip it totrue
if you want to use it. (Firefox bug 887538) - The read-only property
HTMLIFrameElement.sandbox
is no longer a string but aDOMTokenList
(Firefox bug 845057). - On
HTMLCanvasElement.getContext()
, the valuemoz-webgl
is no longer supported. Use the standardwebgl
value (Firefox bug 913597). - The constructor for
ImageData
has been added. This interface can be used in aWorker
. (Firefox bug 959958) - The property
location.origin
is now available in workers (viaWorkerLocation
) (Firefox bug 964148). - The
ValidityState.badInput
property has been implemented (Firefox bug 827161). - The deprecated
Window.pkcs11
property has been removed; it was returningnull
since Firefox 3.0.14. (Firefox bug 964964) - The
Node.cloneNode()
andDocument.importNode()
methods take the Booleandeep
argument. Until now, if omitted, these methods acted as if the value ofdeep
wastrue
. But this behavior has been changed as per the latest spec, and if omitted, the methods will act as if the value wasfalse
. (Firefox bug 937461) Window._content
is no longer available to Web content (Firefox bug 946564).URLUtils.port
behavior has been slightly changed: set to''
will set it to the default port associated with the protocol, and0
to0.
(Firefox bug 930450)Document.referrer
is now based on the incumbent script (Firefox bug 887928).- The Gamepad API is enabled by default (Firefox bug 878828).
- The
CanvasRenderingContext2D.drawSystemFocusRing()
method got renamed toCanvasRenderingContext2D.drawFocusIfNeeded()
(Firefox bug 959820).
MathML
No change.
SVG
No change.
Security
- The CSP 1.1 experimental
hash-source
directive has been implemented. The preferencesecurity.csp.experimentalEnabled
should be set totrue
to enable this functionality (Firefox bug 883975).
Changes for add-on and Mozilla developers
- Major Firefox theme changes affect most extensions that interact with the Firefox user interface.
nsISecurityCheckedComponent
has been removed (Firefox bug 794943). Most consumers can removensISecurityCheckedComponent
from their interface definition and they will continue to work.
Older versions
- 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