The Mozilla project has released Firefox 3 Release Candidate 1 (RC1). New features in Firefox 3 include support for Javascript 1.8, DOM and HTML changes, microformats support, and an extended Canvass implementation.
Mozilla Corporation continues its march toward Javascript 2.0 with the implementation of features from the Javascript 1.8 specification. New feature include: expression closures, generator expressions, and native JSON encoding and decoding. Expression closures are a shorthand method of defining simple functions that mimics lambda notation. Generator expressions make it possible to create generators without defining a custom function. JSON encoding and decoding formalizes into the language itself a now ubiquitous feature in Javascript libraries such as Prototype and jQuery.
The major changes to HTML and the DOM in Firefox 3 are related to security improvements and standards compliance. The Firefox team fixed a security hole that allowed frames and iframes to inherit the parent document's character set. They also addressed vulnerabilities in chrome access by remote hosts and file uploading. New features from the HTML 5 specification are also present in Firefox 3 such as improved drag-and-drop support and new DOM attributes related to focus management.
Firefox 3 has a new global Microformats object accessible to Javascript developers. This API handles the discovery and parsing of some common microformats: adr for address information, geo for spatial coordinates, hCard for contact information, hCalender for calender appointments, and tag which according to the documentation "is used to add tags to other microformats."
Firefox 3 extends the canvass element beyond the official WHATWG specification. Namely, it now provides facilities for drawing text on a canvass surface. Firefox 3 also now supports transformation functions for the canvass objects.
There are additional features in Firefox 3 RC1, include animated PNG (APNG) support. Further details are available at the Mozilla Developer Center. Firefox 3 RC1 can be downloaded from the project website.