Firefox 38 for developers

Firefox 38 was released on May 12th, 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 37 and Firefox 38.

CSS

HTML

  • The <label> element no longer dispatches events to the label target element if interactive content is found between the event target and the label (bugĀ 229925).
  • The <picture> element has been activated by default (bugĀ 1017875).
  • The <meta name="referrer"> is supported for navigations from the context menu or via a middle-click (bugĀ 1113431).

JavaScript

Interfaces/APIs/DOM

MathML

No change.

SVG

No change.

Audio/Video

No change.

Networking

No change.

Security

  • In Firefox, the autocomplete=false attribute is now ignored when dealing with a login form (bugĀ 1025703). This is intended to encourage the use of more secure passwords by allowing password manager tools to work more reliably.
  • RC4 is now disabled when using TLS, except for a few specifically whitelisted Web sites. This whitelist is an interim measure until those sites are fixed (bugĀ 1124039). This fallback is controlled by the security.tls.unrestricted_rc4_fallback preference, true by default for the moment (bugĀ 1138882).
  • Web sites needing to fall back to an insecure version of TLS in order to work are now in a hardcoded whitelist which will shrink over time (bugĀ 1114816). The whitelist can be disabled by setting security.tls.insecure_fallback_hosts.use_static_listĀ  to false.

Changes for add-on and Mozilla developers

Add-on SDK

Highlights

Electrolysis (E10s) updates

Details

XUL

No change.

JavaScript code modules

Downloads.jsm

  • DownloadTarget objects now have exists and size properties, allowing you to determine the existence of and the size of the download's target file on disk, as well as a new refresh() method, which asks that these values be updated.

XPCOM

See also

Older versions