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Firefox 42 was released on November 3, 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:

All devtools bugs fixed between Firefox 41 and Firefox 42.

CSS

HTML

JavaScript

Interfaces/APIs/DOM

DOM & HTML DOM

Service Workers

Web Animations API

Our experimental implementation of Web Animations API have been extended to support:

Web Components

Our experimental implementation of the Shadow DOM has been modified:

WebGL

WebRTC

New APIs

  • The ImageBitmap interface and the createImageBitmap() method have been implemented. They are available on regular window scripts and in Web workers and allow efficient posting of images between window and worker contexts (bug 1044102).

Miscellaneous

MathML

No change.

SVG

No change.

Audio/Video

No change.

HTTP

  • Firefox 41 and earlier versions were incorrectly accepting undefined or invalid pseudo-header fields in HTTP/2 responses. This is now fixed and the only pseudo-header field accepted from Firefox 42 is the :status as per the specification. Response headers containing arbitrary fields are considered malformed. (bug 1136727)

Networking

Security

  • EV certificates with a validity greater than 39 months are now considered and handled as DV certificates (bug 1145679).

Changes for add-on and Mozilla developers

Interfaces

nsIContentPolicy

  • The TYPE_EMBED constant has been added to nsIContentPolicy to allow Gecko internals and add-on code to better differentiate different types of requests. Previously, TYPE_OBJECT was used for these cases (bug 1148030).
  • Similarly, the TYPE_SUBDOCUMENT constants has been split into TYPE_FRAME and TYPE_IFRAME (bug 1148044).

XUL

No change.

JavaScript code modules

No change.

XPCOM

No change.

Other

No change.

See also

Older versions

Document Tags and Contributors

 Last updated by: fscholz,