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Firefox 40 was released on August 11, 2015. This article lists key changes that are useful not only for web developers, but also Firefox and Gecko developers as well as add-on developers.

Changes for Web developers

Developer Tools

Highlights:

More:

Everything: all devtools bugs fixed between Firefox 39 and Firefox 40.

 

CSS

HTML

No change.

JavaScript

Interfaces/APIs/DOM

New APIs

  • The Push API has been experimentally implemented (bug 1038811). Controlled by the services.push.enabled pref, it is disabled by default.

Web Animations API

Improvement in our experimental Web Animations implementation, mostly to match latest spec changes:

CSSOM

  • The CSS Font Loading API is now enabled by default in Nightly and Developer Edition releases (bug 1088437). It is still deactivated by default in Beta and Release browsers.
  • The CSSCharsetRule interface has been removed and such objects are no longer available in CSSOM (bug 1148694). This matches the spec (recently adapted) and Chrome behavior.

WebRTC

DOM & HTML DOM

Web Audio API

New extensions to the Web Audio API:

Web Workers

IndexedDB

Dev Tools

MathML

No change.

SVG

No change.

Audio/Video

No change.

Networking

No change.

Security

  • Using an asterisk (*) in a CSP does not include the schemes data:, blob: or :filesystem anymore when matching source expressions. So those schemes now need to be explicitly defined within the related header to match the CSP (bug 1086999).

Changes for add-on and Mozilla developers

XUL

  • It is no longer possible to create transparent top-level windows bug 1162649.

JavaScript code modules

XPCOM

  • The nsIClassInfo.implementationLanguage attribute has been removed, along with the nsClassInfo::GetImplementationLanguage() function.
  • The following XPCOM interfaces have been removed; you should use the standard HTML interfaces instead:
    • nsIDOMHTMLBRElement
    • nsIDOMDivElement
    • nsIDOMHTMLHeadingElement
    • nsIDOMHTMLTableCaptionElement
    • nsIDOMHTMLTableElement
    • nsIDOMHTMLTitleElement

Other

See also

Older versions

Document Tags and Contributors

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 Last updated by: Sheppy,