Firefox 23 for developers
Changes for Web developers
Security
- Mixed content blocking. Firefox will no longer load non-secure (http) resources on secure (https) pages (Firefox bug 834836).
- The standard syntax of CSP 1.0 policies are now implemented and enforced by default.
Developer Tools
- A Network Panel has been added to the developer tools. This is more detailed view than the "Net" view option in the Web Console.
- Web Console has been renamed "Console", and includes the option to filter security errors/warnings.
- The new Toolbox Options lets you disable features, change light/dark theme, or enable Chrome/Remote debugging.
HTML
- The
<blink>
element support is now completely dropped. The<blink>
tag now implements theHTMLUnknownElement
interface (Firefox bug 857820). - The
range
type of the<input>
element (<input type="range">
) has been switched on by default (Firefox bug 841950).
JavaScript
- The
Object.defineProperty
method can now be used to redefine thelength
property of anArray
object. - The option to disable JavaScript, including the options to allow moving windows/replace context menu, have been removed. You may still disable JavaScript by double clicking the "javascript.enabled" option in about:config.
DOM
- D3E
KeyboardEvent.key
is now supported, but only for non-printable keys (Firefox bug 842927). - The
title
attribute ofDOMImplementation.createHTMLDocument
is now optional as per updated DOM specification. - The ability to add a sidebar panel (
window.sidebar.addPanel
) has been dropped (Firefox bug 691647). - The unprefixed
Window.requestAnimationFrame
andWindow.cancelAnimationFrame
methods has been added (Firefox bug 704063). The unprefixedWindow.requestAnimationFrame
receives aDOMHighResTimeStamp
as argument; the prefixed version receives a timestamp in milliseconds (Firefox bug 753453). - The text argument for
window.alert
andwindow.confirm
is now optional (Firefox bug 861605). - The
HTMLMediaElement.initialTime
property, removed from the spec, is no more supported (Firefox bug 742537). - The
AnimationEvent()
constructor has been added (Firefox bug 848293). - The
AnimationEvent.pseudoElement
property has been implemented (Firefox bug 848293). - The
TransitionEvent()
constructor has been added (Firefox bug 848291). - The
TransitionEvent.pseudoElement
property has been implemented (Firefox bug 848291). - The non-standard
TransitionEvent.initTransitionEvent()
andAnimationEvent.initAnimationEvent()
have been removed (Firefox bug 868751).
WebRTC
- Instead of including usernames in the
RTCIceServer.url
property (such as stun:username@stunserver.example.com), you now need to use the newRTCIceServer.username
property.
CSS
- The blink effect for
text-decoration: blink;
has no more effect, but is still a valid value (Firefox bug 857820). - In-flow
::after
and::before
pseudo-elements are now flex items (Firefox bug 867454). - The way to compute viewport units has been changed. In conjunction with
overflow:auto
, space taken by eventual scrollbars is not subtracted from the viewport, whereas in the case ofoverflow:scroll
, it is. (Firefox bug 811403)
MathML
- Negative widths for the
<mspace>
element has been implemented (Firefox bug 717546). - The
<semantics>
element now determines the visible child as described in the MathML3 specification.
Changes for addon and Mozilla developers
Firefox developer tools
Addons that overlay chrome://browser/content/debugger.xul must now overlay chrome://browser/content/devtools/debugger.xul. You may add references to both these files in chrome.manifest for compatibility.
See also
Older versions
- 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