YSlow 2.1.0 release

YSlow 2.1.0 is now available (courtesy of Marcel Duran). There are major bug fixes in this release, as well as making YSlow compatible with Firefox 4.

YSlow is a Firefox add-on integrated with the Firebug web development tool. It analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages.

YSlow analyzes web pages and suggests ways to improve their performanceyslow-1010

Summary of bugs fixed

  • Compatible with latest Firefox 3.6., as well as Firefox 4 Beta.
  • Compatible with Firebug 1.6 beta
  • Updated JSLint version (2010-09-16)
  • Improved error message display (removed pop-up, using console instead for error message)
  • Fixed some infinite loops issues for redirects and some autorun weird behavior.
  • Added new rule for detecting empty src or href (<img src='' >, <link href=””>, and <script src=””>) as suggested in Nicholas Zakas' NCZOnline.
  • Added logic to not consider deferred scripts on head as offenders — previous version of YSlow complains when scripts tags are inserted dynamically into the HEAD tag. Such scripts do not block page rendering and are downloaded in parallel with other resources.
  • Fixed inconsistency in displaying Expires date inside YSlow report Summary View column
  • Fixed “JavaScript at bottom rule” issue — previous version of YSlow complains when scripts tags are inserted dynamically into the HEAD tag, now it doesn't consider dynamically injected scripts into HEAD
  • Fixed issue running JSLint from a page loaded from a previous about:blank

Download YSlow 2.1.0 and contact us on the Exceptional Performance Yahoo! group for any questions and to provide feedback.