Firefox 23 for developers

Sie lesen die englische Version dieses Inhalts, da für dieses Gebietsschema noch keine Übersetzung vorhanden ist. Helfen Sie uns, diesen Artikel zu übersetzen!

Changes for Web developers


  • Mixed content blocking. Firefox will no longer load non-secure (http) resources on secure (https) pages (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.



  • The Object.defineProperty method can now be used to redefine the length property of an Array 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.




  • The blink effect for text-decoration: blink; has no more effect, but is still a valid value (bug 857820).
  • In-flow ::after and ::before pseudo-elements are now flex items (bug 867454).
  • The way to compute viewport units has been changed. In conjunction with overflow:auto, space taken by eventual scrollbars is not substracted from the viewport, whereas in the case of overflow:scroll, it is. (bug 811403)


  • Negative widths for the <mspace> element has been implemented (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