Firefox 14 for developers

Firefox 14 shipped on July 17, 2012. This article lists key changes that are useful for not only Web developers to know about, but also Firefox and Gecko developers as well as add-on developers.

Changes for Web developers


  • <progress>元素不在错误的归为一个表单元素,因此不再有一个form属性。
  • The default modifier keys for the accesskey of HTML contents on Mac are changed to Control+Option. This is the same as WebKit-based browsers on Mac.


  • input events are fired also on editing host element of contenteditable editor and root element of designMode editor.
  • DOMException.code已被废弃,根据最新的 DOM Level 4 规范。
  • Range.insertNode() method now works correctly when used on collapsed ranges.
  • The MozBlobBuilder interface has been deprecated in favor of the constructor on Blob. If you use MozBlobBuilder you'll see a warning message in the Web Console.
  • The Blob() constructor is now available to workers (Firefox bug 736686).
  • Support for the Mutation Observers has been landed. It is designed as a replacement for the Mutation Events in DOM3, which has a number of issues regarding performance.
  • The HTMLImageElement interface's x and y properties were removed in Gecko 7.0 but restored in this release for compatibility reasons.
  • Document上的方法execCommandShowHelp()queryCommandText(),没有任何作用,已被删除。
  • The GeoPositionAddress interface, an obsolete part of the Geolocation API, has been removed.
  • localStorage/sessionStorage now correctly return undefined instead of null for undeclared keys through property access.
  • The ImageData object has been implemented (Firefox bug 550309).
  • Attributes and methods related to child nodes on Attr interface where obsoleted (Firefox bug 737122).


  • The text-transform and font-variant CSS properties have been fixed to correctly handle the iİ and ıI Turkic-specific case pairs.
  • The Dutch IJ digraph is now correctly handled by text-transform: capitalization. Similarly the Greek letter Σ, which has two lowercase forms, σ and ς, is now correctly handled by text-transform: lowercase.
  • Support for the skew() function has been removed from transform property, as it has been removed from the draft standard.
  • The syntax for border-image has been updated to match the latest revision of the specification; it no longer accepts a trailing slash ("/").


No change.


  • The syntax of the statusline action type on <maction> elements has been adjusted to follow the MathML specification.


  • Gecko 开始支持新的HTTP 308 永久重定向 状态码。由于 Gecko 并不区分永久重定向和临时重定向,所以该状态码的表现行为和307 临时重定向状态码是一样的,和 302 以及 301 状态码的区别是,它们禁止用户代理改变重定之后的 HTTP 方法 (POST 还是 POST, GET 还是 GET).

Changes for Mozilla and add-on developers

JavaScript 代码模块


  • Added a keyboard shortcut to toggle commenting for the current selection (Ctrl-/ or Cmd-/ on Mac OS X).
  • Added the Ctrl-[ and Ctrl-] keyboard shortcuts for moving the text input position to the beginning and end of the current block.
  • Added the new getLineStart() and getLineEnd() methods.


  • <window> 元素上添加了新的 fullscreenbutton 属性;将该属性设置为true,会在窗口上添加一个进入全屏模式的按钮。


  • nsILocalFile接口被合并到nsIFile接口中。(bug 682360).
  • The methods in nsIPlacesImportExportService for importing bookmarks have all been removed in favor of the BookmarkHTMLUtils.jsm JavaScript code module.
  • nsIDOMGeoPositionAddress 接口已被移除。


  • Dictionary names are now parsed as full BCP 47 language tags (bug 730209, bug 741842). Developers are encouraged to not hard-code the name of their language in their dictionary names.