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.
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 (bug 846601).
- On the Inspector, preview tooltips of CSS transforms are now available (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 (bug 926014).
- Autocompletion of CSS properties and values has been added to the Style Editor (bug 717369).
See the Mozilla Hacks blog post for details and other smaller changes.
- CSS variables have been implemented (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
trueif you want to play with them).
- Flexboxes now support
: collapse(bug 783470).
box-sizingproperty has been unprefixed (bug 243412).
will-changeproperty, a hint to that something will animate has been added. The preference
layout.css.will-change.enabledmust be switched to
trueto enable it. (bug 940842)
- Scientific exponential notation, like
10e+0, is now supported for
<number>values and derivatives, like
<percentage>and unit values, but not
- Images of type
<gradient>are now supported in
touch-actionproperty has been implemented. It is not activated by default; the
layout.css.touch_action.enabledpref controls it. (bug 795567)
- Remove redundant default style for <pre> element from quirk.css (bug 948914).
- CSS Variables fallback incorrectly implemented (primary cycles) (bug 950497).
- @supports conditions with tokens after a declaration's priority should evaluate to false (bug 909170).
<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. (bug 949879)
- New ECMAScript 2015 String methods:
String.prototype.fromCodePoint()have been implemented (bug 918879).
- The ECMAScript Internationalization API (ECMA-402) has been implemented and is now enabled by default in Firefox Desktop (bug 853301):
- New objects in the new
- The following methods of
Datehave been updated to include the
optionsarguments per ECMA-402:
- New objects in the new
- To match the updated ECMAScript 2015 draft specification, the
Setobjects now treat
+0as the same when checking for key and value equality.
Promisehas been enabled by default (bug 918806).
- Completed generators now return an
IteratorResultobject instead of throwing (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.
ArrayBuffer.isView()method has been added (bug 896105).
- A new type of workers,
SharedWorker, is now available by default (bug 924089).
URLUtilsinterface now supports the
searchParamsproperty returning a
URLSearchParamsobject, allowing to modify the search params of an URL (bug 887836). The
URLSearchParamsconstructor allows easier parsing of query strings.
NavigatorOnLine.onLineproperty is now supported on
WorkerNavigator, allowing to know the online/offline status in workers (bug 925437).
- As part of the implementation of Web Components, the
HTMLShadowElementinterface has been implemented behind the
dom.webcomponents.enabled. Flip it to
trueif you want to use it. (bug 887538).
- The read-only property
HTMLIFrameElement.sandboxis no longer a
HTMLCanvasElement.getContext(), the value
moz-webglis no longer supported. Use the standard
webglvalue (bug 913597).
- The constructor for
ImageDatahas been added. This interface can be used in a
Worker. (bug 959958)
- The property
location.originis now available in workers (via
WorkerLocation) (bug 964148).
ValidityState.badInputproperty has been implemented (bug 827161).
- The deprecated
Window.pkcs11property has been removed; it was returning
nullsince Firefox 3.0.14. (bug 964964)
Document.importNode()methods take the Boolean
deepargument. Until now, if omitted, these methods acted as if the value of
true. But this behavior has been changed as per the latest spec, and if omitted, the methods will act as if the value was
false. (bug 937461)
Window._contentis no longer available to Web content (bug 946564).
URLUtils.portbehavior has been slightly changed: set to
''will set it to the default port associated with the protocol, and
Document.referreris now based on the incumbent script (bug 887928).
- The Gamepad API is enabled by default (bug 878828).
CanvasRenderingContext2D.drawSystemFocusRing()method got renamed to
- The CSP 1.1 experimental
hash-sourcedirective has been implemented. The preference
security.csp.experimentalEnabledshould be set to
trueto enable this functionality (bug 883975).
- Australis and add-on compatibility - This is a major Firefox theme change that affects most extensions that involving the Firefox user interface.
nsISecurityCheckedComponenthas been removed (bug 794943). Most consumers can remove nsISecurityCheckedComponent from their interface definition and they will continue to work.
Non-Australis changes TBD.
- Firefox 28 for developers
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- 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