This actually could be used quite easily with Silverlight and an AgTweener could be very easily created from this. The Tweener like syntax with an object and adding tweens of available properties as an object or array is very simple and could make animation systems much more standard if everything used this not to mention easier for developers to animate in any presentation layer. The syntax makes for the best of the Animation Packages currently available for AS3. If this could be used in other kits it would make animation pretty standard and simple when changing platforms.

JQuery is very lightweight and has a similar syntax on their animate() call. There are many animation javascript kits such as mootools, jquery, dojokit and prototype and others that have similar functionality but it is all handled differently.

JSTweener

• http://coderepos.org/share/wiki/JSTweener
• http://svn.coderepos.org/share/lang/javascript/jstweener/trunk/examples/index.html

JSTweener.addTween(element.style, {
time: 3,
transition: 'linear',
onComplete: function() {},
width: 200,
height: 200,
left: 500,
top: 300
});

JSTweener Source

JSTweenerRepo

Samples:

• transitions
• mtypo_bezier
• mtypo

Found via Zeh

Check out the Silverlight demos here:

DojoX

• high quality implementations of previously experimental features: gfx (portable 2D drawing), data wires, offline, storage, cometd, etc.
• dojox.gfx now includes Sliverlight support
• many more features and improvements than there’s room for here.

Dijit

• unified look and feel for all widgets
• ambitious a11y and i18n features in every Dijit widget
• a mature CSS-driven theme system with multiple, high-quality themes
• huge improvements in system performance
• data-bound widgets
• Declarations for lightweight widget writing
• a new page parser that allows instances of any class, not just widgets
• no magic

Core

• reduced API surface area (easier to remember and use)
• dojo.query() always available, returns real arrays
• from-scratch high-performance DnD system
• Base (dojo.js) is 25K on the wire (gzipped)
• dojo.data APIs finalized
• new build system
• new test harness for both CLI and browser use
• dojo.behavior now marked stable and based on dojo.query
• excellent animation APIs with Color animations in Base (always available)
• all the features you’ve come to count on from Dojo (RPC, JSON-P, JSON, i18n, formatting utilities, etc.)

[ source ]

My results are very similar to Bubblemarks tests:

JavaFX — 14 fps
Firefox + Silverlight (JavaScript) — 56 fps
Firefox + Flex — 62 fps
Adobe AIR — 62 fps
Firefox + Silverlight (CLR) — 99 fps

Silverlight is not final and is quite light compared to Flex (I wonder if a vanilla Flash9/AS3 export has been done or if it would perform any different), but if Silverlight has a lead on FPS, where FPS is really success of any kit in RIA or vector, then it could be a rough battle. Flash/Flex is really far far ahead due to the browser penetration and the development community but the better performance is always a good indicator of possible success. Plus, Microsoft controls the desktop market and any “benefits” it might give their own kit which includes distribution and performance in preloading or caching.