MochiKit

All the good ideas and programming methods were taken from Python, Objective-C, etc. experienced and adapted into the world of JavaScript.

Features:

• Reliable:
• MochiKit has HUNDREDS of tests. We build real applications with this thing. So even though development can move fast, we make sure to get tests written. This also makes platform compatibility issues much easier to detect and resolve than the "guess and check" style of quality assurance seen in some of the other libraries out there. It's not broken.
• Documented:
• It's unlikely to find any JavaScript code with better documentation than MochiKit. 100% documentation coverage for all of MochiKit at all times is maintained.
• Evolutionary:
• MochiKit can adapt to anything it is thrown at. It makes no assumptions about how code needs to act, and it has hooks (by way of the the adapter registries) that makes sure that the developer can define his own comparisons, programming representations, iterators, or DOM node coercion for any object in any way he wishes.
• Plays well with others:
• Although MochiKit can be, and often is, used as a one stop shop for JavaScript goodness; it is very highly interoperable. MochiKit does no Object.prototype hacking, and inserts just three symbols (the MochiKit namespace, plus the compare and reduce functions to work around JScript bugs) into the global namespace. As far as server-side goes, MochiKit is totally agnostic. However, feel free to include MochiKit as part of the AJAX arsenal - TurboGears does out of the box!
• Compatibility:
• The current test platforms include all of the modern and popular browsers: Safari 2.0.2, Firefox 1.0.7, Firefox 1.5b2, Internet Explorer 6, and Opera 8.5. Other JavaScript platforms should work if they're standards compliant (ECMA-262 and the W3C DOM ECMAScript binding, primarily).

What is new in this release:

• Changed default packed version to contain all modules (since easy customization is now available).
• More fixes in MochiKit.Style.getElementDimensions for IE and hidden elements
• Fixed issue in MochiKit.Style.getViewportDimensions when called within the document HEAD
• Fixed MochiKit.DOM.coerceToDOM() handling of arrays when MochiKit.Iter is not loaded