Yahoo has released the latest version of its Firebug extension ‘YSlow’. The YSlow 2.1.0 version reportedly comes with major bug fixes. For the uninitiated, YSlow is a Firefox add-on integrated with the Firebug web development tool. It is a page analysis tool aimed at enabling users to optimize their web pages and improve their performance.

Here’s a summary of the bugs fixed as revealed in the Yahoo Developer Network:

• Compatible with Firefox 3.6, as well as Firefox 4 Beta.
• Compatible with Firebug 1.6 beta
• Updated JSLint version
• Improved error message display (removed pop-up, using console instead for error message)
• Fixed certain 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=””>).
• 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.