Firefox 20 for developers
Firefox 20 was released on April, 2nd 2013. This article provides information about the changes in this release that will affect developers.
Changes for Web developers
HTML
- Support for the
download
attribute on the<a>
and<area>
element has been added (Firefox bug 676619). - The value
auto
for the global attributedir
has been implemented (Firefox bug 548206). - The global attribute contextmenu now works on Firefox for Android (Firefox bug 736321).
JavaScript
- Support for the
WeakMap.prototype.clear()
method, recently added to the Harmony (ECMAScript 2015) draft proposal has been added (Firefox bug 814562). - Support for the
Math.imul()
method, a C-style 32-bit multiplication function. Though proposed for Harmony (ECMAScript 2015) it has not yet accepted and still is non-standard (Firefox bug 808148). - Web apps using draggable text with Kinetic 3.x are working, even when using the Cairo canvas backend (Firefox bug 835064).
- The
for each...in
statement has been deprecated and should not be used. Consider using the newfor...of
statement (Webkit bug 804834). - Support for the
Map.prototype.keys()
,Map.prototype.values()
, andMap.prototype.entries()
has been added (Firefox bug 817368).
CSS
- CSS Flexbox is now available by default in pre-release builds only (excluding beta versions). It can be enabled in release and beta version by setting the
layout.css.flexbox.enabled
about:config preference totrue
. - The
mask-type
property from the CSS Masking specification has been added (Firefox bug 793617). - Experimental support for the
:scope
pseudo-class has been added. Enabled by default in Aurora and Nightly, it can be enabled in release and beta version by setting thelayout.css.scope-pseudo.enabled
about:config preference totrue
(Firefox bug 648722).
DOM/APIs
HTMLMediaElement
supports nowplaybackRate
(both read and write), with pitch correction. Pitch correction can be controlled using the propertymozPreservesPitch
(Firefox bug 495040).- CSSOM: Support for the new
CSSGroupingRule
andCSSConditionRule
has been added (Firefox bug 814907). - CSSOM: On
CSSRule
the constant CSSRule.MOZ_KEYFRAME_RULE and CSSRule.MOZ_KEYFRAMES_RULE have been unprefixed to CSSRule.KEYFRAME_RULE and CSSRule.KEYFRAMES_RULE. The prefixed version are temporarily kept for helping Web author to transition their code Firefox bug 816431). - CSSOM: It is now possible to set the value of
conditionText
forCSSMediaRule
(Firefox bug 815021). - The
DOMParser
parseFromStream
andparseFromBuffer
methods are no longer available from web content (Firefox bug 816410). - The
XMLSerializer
serializeToStream
method is no longer available from web content (Firefox bug 816410). TextDecoder
andTextEncoder
interfaces are now available in Workers (Firefox bug 795542).- Support for the
CSS.supports()
method has been added, behind thelayout.css.supports-rule.enabled
pref (off by default) (Firefox bug 779917). - Support for UndoManager has been added (Firefox bug 617532).
- The CSSOM
Document.caretPositionFromPoint()
method, which returns aCaretPosition
has been implemented. - The index argument of the
tableRow.insertCell
andtable.insertRow
methods has been made optional as per HTML specification. Navigator.getUserMedia
, still prefixed asNavigator.mozGetUserMedia
is now activated by default.- The third, optional,
transfer
argument ofWindow.postMessage
is now supported. It allows to transfer a sequence ofTransferable
objects to the destination (Firefox bug 822094). - The non-standard
Window.sizeToContent()
method now clamps the minimal size: the window cannot be forced anymore to small sizes preventing the user to interact with (Firefox bug 764240). - Blend modes, such as
overlay
,color-burn
,hue
, etc. have been added to the CanvasCanvasRenderingContext2D.globalCompositeOperation
property (Firefox bug 748433). - The prefixed version of
window.indexedDB
—window.mozIndexedDB
— was reintroduced to Gecko, so that bad cross-browser prefixing code (such asvar indexedDB = window.indexedDB || window.webkitIndexedDB …
) doesn't break in Firefox. A better approach iswindow.indexedDB = window.indexedDB || window.webkitIndexedDB …
(see Firefox bug 770844.)
SVG
- The implementation of the
contentScriptType
andcontentStyleType
properties has been removed fromSVGSVGElement
along with the removal from SVG2 (Firefox bug 819731).
MathML
- To help MathML authors debugging "invalid-markup" errors in their documents, MathML parsing errors (such as having too many / too few child elements) and warnings about deprecated attributes or wrong attribute values are now reported to the Error Console.
- The
scriptminsize
attribute now accepts unitless values and percent values. They are interpreted as multiples of the default value ("8pt
"). - Unitless values are now also allowed for the
mathsize
andfontsize
attributes; they multiply the default value.
Changes for add-on and Mozilla developers
- ECMAScript for XML (E4X) is now fully disabled for all chrome and content scripts. It was previously disabled for content in Firefox 17 and has been removed entirely for Firefox 21. Use DOMParser/DOMSerializer or a non-native JXON algorithm instead.
- The
nsIDOMParserJS
interface no longer exists (Firefox bug 816410). SeensIDOMParser
for alternatives. - Content Preferences: The
nsIContentPrefService
interface is now deprecated and the asynchronousnsIContentPrefService2
storage API has been implemented. - The
nsIProfile
andnsIProfileChangeStatus
interfaces have been removed, along with other code supporting the pre-Firefox profile management system. You probably weren't using these interfaces, but if you were, you should stop doing so. This prevents defunct parts of the profile management system from vetoing the shutdown process. - The
nsIEventSource
interface no longer exists (Firefox bug 819639).
See also
Older versions
- 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