Ajax Girl

Sam and the team have put out a Prototype 1.5.1 release candidate available to download here.

One of the good changes is a sign of good community. Prototype was inspired by the CSS selector performance data that Jack Slocum and others have been talking about.

Now $$/Selector is up to 5 times faster depending on the task / browser.

New features and changes

• $$ now supports virtually all of CSS3, with the exception of some pseudo-elements (like ::first-letter) and some pseudo-classes (like :hover).
• Prototype now has support for JSON encoding and decoding built in. If you’ve had issues with the official json.js library extending Object.prototype, you can now use our implementation instead. Thanks Tobie!
• Element.extend can now take a tag name or array of tag names as its first argument to apply the given methods to specific tags.
• Added String#empty, String#blank, String#startsWith, String#endsWith, String#include, and String#times.
• Added Number#toPaddedString.
• Added Form#request, which uses the form’s action and method attributes, along with its serialized parameters, to create an Ajax.Request.
• Removed support for “throw $continue” in Enumerable iterators. If you were using this in your scripts, please replace it with “return” instead.

Performance improvements

• $$ is now blazing fast. Seriously—try it out. If you’re using $$ at all, you owe it to yourself to upgrade! Element#down, Element#up, Element#previous and Element#next received performance boosts too (along with everything else that uses Selector).
• Element#getStyle and Element#setStyle are now faster.
• Array#uniq is faster. [#7417]
• String#escapeHTML now uses a cached div and text node, making it much faster. [#6937]
• Enumerable iteration is faster now that it incurs only one try/catch block instead of two (as a result of removing support for $continue).

Source: Ajaxian
Original Article: http://ajaxian.com/archives/prototype-151-release-candidate-released