Firefox 17 for developers

Firefox 17 shipped on November 20, 2012. This article lists key changes that are useful for not only web developers, but also Firefox and Gecko developers as well as add-on developers.

Changes for Web developers

HTML

Support for the sandbox attribute on the <iframe> element has been added. (bug 341604)

CSS

Support for @supports at-rule defined in CSS3 Conditional Rules specification has been landed. It is disabled by default. Developers can try it by setting layout.css.supports-rule.enabled to true (bug 649740).
Support for the CSS Selectors Level 4 pseudo-class :dir() allowing selection of elements based on their directionality has landed. (bug 562169)
Support for the newly specified isolate-override value of the CSS unicode-bidi value has landed (bug 774335)
Our prefixed implementation of box-sizing now takes into account min-height and max-height. One step closer to its unprefixing (bug 308801)

DOM/APIs

Support for CSSSupportsRule interface defined in CSS3 Conditional Rules specification has been landed (bug 649740)
Support for WheelEvent object and wheel event have been landed (bug 719320).
Support DOM Meta key on Linux again (bug 751749).
On HTMLMediaElement, a new method, mozGetMetadata, that returns a javascript object whose properties represent metadata from the playing media resource as {key: value} pairs (bug 763010).
Support for Range.intersectsNode has been added again; it has been removed in Gecko 1.9 (bug 579638.
Range.compareBoundaryPoints() now throws a DOMException with the NOT_SUPPORTED_ERR value when the comparison method is invalid (bug 714279) .
Event.initEvent() has been adapted to the spec: it doesn't throw anymore if called after the dispatch of the event, it is only a no-op (bug 768310).
The non-standard XMLHttpRequest.onuploadrequest property has been removed (bug 761278).
The method XMLHttpRequest.getAllResponseHeaders() now separates them with a CRLF (instead of a LF), as requested by the spec (bug 730925).

JavaScript

String object now offers Harmony startsWith, endsWith, and contains methods (bug 772733).
The String methods link and anchor now escape the '"' (quotation mark) (bug 352437).
Experimental support for strawman ParallelArray object has been implemented (bug 778559).
Support to iterate Map/Set (bug 725909).
Disabled E4X for web content by default (bug 778851).
__exposedProps__ must now be set for Chrome JavaScript objects exposed to content. Attempts to access Chrome objects from content without __exposedProps__ set will fail silently (bug 553102).
for..of loops now work in terms of .iterator() and .next() (bug 725907).

WebGL

The EXT_texture_filter_anisotropic WebGL extension has been unprefixed. Using "MOZ_EXT_texture_filter_anisotropic" will present a warning from now on. The prefixed name is going to be removed in a future release (bug 776001).

SVG

No change.

MathML

The parsing of the align attribute on <mtable> elements has been updated to treat optional spaces more correctly.

XUL

XUL key element supports "os" modifier which is Win key (Super or Hyper key) (bug 778732).

Network

Removed the the non-standard feature XMLHttpRequest.onuploadprogress which was deprecaed in Firefox 14.

No change.

Developer tools

Change JSTerm's $ helper function from getElementById to querySelector() (bug 751749).

User Agent

The Gecko part of the user agent string changed. The build date (which hadn't been updated since 2010) was removed, and the Gecko version number was put in its place instead. So Gecko/20100101 -> Gecko/17.0. This may affect you if you are doing user agent sniffing.

Changes for add-on and Mozilla developers

Interface changes

nsIInputStream: The available() method returns 64-bit length instead of 32-bit (bug 215450).
nsIDOMWindowUtils: The sendMouseScrollEvent() method has been replaced with sendWheelEvent() (bug 719320).
nsIFilePicker: The open() method, to open the file dialog asynchronously, has been added and the show() method has been deprecated (bug 731307).
nsIScriptSecurityManager: The checkLoadURIStr() and checkLoadURI() methods have been removed (bug 327244).
nsIRefreshURI: The setupRefreshURIFromHeader() method has a added principal parameter (bug 327244).

New interfaces

None.

Removed interfaces

None removed.