Appearance Panel access in javascript

Although unfortunately we are not supplied with any scripting control over the appearance palette, it is possible to manipulate the appearances of artwork in some ways.

First, there is no editing of any appearances in the literal sense as there's no scripting interface available for the usage of the appearance panel in a similar way that a user might use it. All that is possible is using graphic styles, menu commands that have anything to do with graphic styles and maybe even the cryptic feature Re: PageItem.applyEffect(LiveEffectXML)  Live Effect XML.

It is possible to capture new graphic styles and to apply them in various ways via the additive or replacement mode during script execution.

So it is theoretically possible to get art to grow some new multi-fill appearances by using temporary art with a (possibly dynamically-changed) fill and any other effects, capturing a new graphic style and adding it to the subject artwork using the GraphicStyle .applyTo() or mergeTo() methods. In an extended usage of the same, a follow-up of one or a series of Live Effect XML commands could be used to style that single fill before it is then added to the main artwork with the 'mergeTo()' command.

This is all somewhat speculative, but should make for a unique and fun test exercise.