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.
- Support for the
WeakMap.prototype.clear()method, recently added to the Harmony (ECMAScript 2015) draft proposal has been added (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 (bug 808148).
- Web apps using draggable text with Kinetic 3.x are working, even when using the Cairo canvas backend (bug 835064).
for each...instatement has been deprecated and should not be used. Consider using the new
for...ofstatement (bug 804834).
- Support for the
Map.prototype.entries()has been added (bug 817368).
- 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.enabledabout:config preference to
mask-typeproperty from the CSS Masking specification has been added (bug 793617).
- Experimental support for the
:scopepseudo-class has been added. Enabled by default in Aurora and Nightly, it can be enabled in release and beta version by setting the
layout.css.scope-pseudo.enabledabout:config preference to
playbackRate(both read and write), with pitch correction. Pitch correction can be controlled using the property
- CSSOM: Support for the new
CSSConditionRulehas been added (bug 814907).
- CSSOM: On
CSSRulethe 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 bug 816431).
- CSSOM: It is now possible to set the value of
parseFromBuffermethods are no longer available from web content (bug 816410).
serializeToStreammethod is no longer available from web content (bug 816410).
TextEncoderinterfaces are now available in Workers (bug 795542).
- Support for the
CSS.supports()method has been added, behind the
layout.css.supports-rule.enabledpref (off by default) (bug 779917).
- Support for UndoManager has been added (bug 617532).
- The CSSOM
Document.caretPositionFromPoint()method, which returns a
CaretPositionhas been implemented.
- The index argument of the
table.insertRowmethods has been made optional as per HTML specification.
Navigator.getUserMedia, still prefixed as
Navigator.mozGetUserMediais now activated by default.
- The third, optional,
Window.postMessageis now supported. It allows to transfer a sequence of
Transferableobjects to the destination (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 (bug 764240).
- Blend modes, such as
hue, etc. have been added to the Canvas
CanvasRenderingContext2D.globalCompositeOperationproperty (bug 748433).
- The prefixed version of
window.mozIndexedDB— was reintroduced to Gecko, so that bad cross-browser prefixing code (such as
var indexedDB = window.indexedDB || window.webkitIndexedDB …) doesn't break in Firefox. A better approach is
window.indexedDB = window.indexedDB || window.webkitIndexedDB …(see bug 770844.)
- 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.
scriptminsizeattribute now accepts unitless values and percent values. They are interpreted as multiples of the default value ("
- Unitless values are now also allowed for the
fontsizeattributes; they multiply the default value.
- 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.
nsIDOMParserJSinterface no longer exists bug 816410. See
- Content Preferences: The
nsIContentPrefServiceinterface is now deprecated and the asynchronous
nsIContentPrefService2storage API has been implemented.
nsIProfileChangeStatusinterfaces 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.
nsIEventSourceinterface no longer exists bug 819639.
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