Firefox 21 release notes for developers

Changes for Web developers

HTML

• The scoped attribute has been added to the <style> element. It allows to include styles that are isolated from the rest of the document. Such styles can be selected using the :scope CSS pseudo-element introduced in Firefox 20. (Firefox bug 508725).
• The new HTML <main> element has been implemented (Firefox bug 820508).

JavaScript

• ECMAScript for XML (E4X), an ancient JavaScript extension, has been removed. Implemented only in Gecko, it never got significant traction (Firefox bug 788293).
• parseInt no longer treats strings with leading "0" as octal (Firefox bug 786135).

CSS

• The none value of -moz-user-select has now the same behavior than the -moz-none value, aligning Gecko on WebKit (Chrome, Safari), Presto (Opera) and Trident (Internet Explorer) (Firefox bug 816298).
• On XHTML content, the auto value of -moz-hyphens incorrectly applied hyphenation rules when the language was not explicitly declared. This is fixed by (Firefox bug 702121).
• An auto value has been added to the CSS -moz-orient property. The auto value is equivalent to horizontal when applied to <meter> and <progress> (Firefox bug 835883).
• The media query -moz-windows-glass has been added on Windows 7 and earlier Windows system (Firefox bug 816803).

DOM

• Support for RTCPeerConnection (as MozRTCPeerConnection) is now enabled by default (Firefox bug 796463). It can be disabled again if necessary by setting media.peerconnection.enabled to false.
• The origin property has been added to the window.location (Firefox bug 828261).
• The valueAsDate and valueAsNumber methods have been added for <input type="time"> (Firefox bug 781570).
• The min and max attributes now apply to <input type="time"> too (Firefox bug 781572).
• Some new keyCodes for volume control are supported (Firefox bug 674739).
• Some new keyCodes for ancient keyboard layout such as AS/400 are now supported on Windows and Linux (Firefox bug 833719).
• Various keyCode values for OEM specific keys on Windows are now supported again (Firefox bug 833719).
• The function window.crypto.getRandomValues has been implemented (Firefox bug 440046).
• The non-standard methods NodeIterator.expandEntityReferences() and TreeWalker.expandEntityReferences() have been removed (Firefox bug 672190).
• CSSOM: the method CSSKeyframesRule.insertRule() has been removed to CSSKeyframesRule.appendRule() to match a spec change (Firefox bug 841896).
• CSSOM If the given parameter given to CSSStyleSheet.insertRule contains more than one rule, a DOMException with a SYNTAX_ERR is now thrown (Firefox bug 765599).
• Until now, when the same headers were repeatedly set with XMLHttpRequest.setRequestHeader, the last-specified value was used. This behavior has been changed to comply with the spec, so those values will be properly combined (Firefox bug 819051).

SVG

• The paint-order attribute has been implemented (Firefox bug 828805).
• The svg.smil.enabled preference has been removed. SMIL is always on. (Firefox bug 835030)

Networking

• We continue to update our CSP implementation to match the CSP 1.0 spec, which reached Candidate Recommendation:
  • Support for the spec-compliant Content-Security-Policy HTTP header (in addition to the experimental X-Content-Security-Policy) has been added (Firefox bug 783049).

    Note: The patch for this new header landed in Firefox 21, it is disabled on builds (Firefox bug 842657).

Worker

• The functions URL.createObjectURL() and URL.revokeObjectURL() are now included in the set of functions available to workers.

Changes for add-on and Mozilla developers

• FUEL applications cannot use the Livemarks service anymore (Firefox bug 834492). The Livemarks service is deprecated and phased out in favor of the new async interface.

• resource:///modules/ and resource://gre/modules/ are no longer identical (Firefox bug 755724). This change was made because of work on the metro version of Firefox. If you load modules using resource:///modules/, you should check if you now want to use resource://gre/modules/ instead. Note that some modules also moved from Firefox to Toolkit (Firefox bug 840287 and Firefox bug 811548 moved NewTabUtils.jsm and the thumbnail modules, respectively).

• The Add-on SDK is now included in Firefox (Firefox bug 731779)

• History API saw numerous deprecated API being removed:

  • Replaced by mozIAsyncFavicons:

    • nsIFaviconService::setFaviconUrlForPage
    • nsIFaviconService::setFaviconData
    • nsIFaviconService::getFaviconData
    • nsIFaviconService::getFaviconForPage
    • nsIFaviconService::setAndLoadFaviconForPage
    • nsIFaviconService::getFaviconImageForPage
    • nsIFaviconService::getFaviconDataAsDataURL

  • Replaced by mozIAsyncLivemarks:

    • nsILivemarkService::*
    • PlacesUtils.itemIsLivemark
    • PlacesUtils.nodeIsLivemarkContainer
    • PlacesUtils.nodeIsLivemarkItem

  • Removed only third argument:

    • PlacesUIUtils.showBookmarkDialog

  • No more implemented by Places, use mozIAsyncHistory instead:

    • nsIGlobalHistory2::addURI
    • nsIGlobalHistory2::isVisited
    • nsIGlobalHistory2::setPageTitle

  • No more needed, use onDeleteURI or onItemRemoved:

    • nsINavHistoryObserver::OnBeforeDeleteURI
    • nsINavBookmarkObserver::OnBeforeItemRemoved

  • Never implemented properly:

    • nsINavHistoryFullVisitResultNode

  • Deprecated, use mozIAsyncHistory::updatePlaces instead:

    • nsINavHistoryService::AddVisit

• Added nsIHttpChannel.redirectTo to enable redirecting HTTP channels without fragile hacks.

See also

• Firefox 21 Release Notes
• Add-on Compatibility for Firefox 21