The possibility of transcoding ABC -> JS (rather than AS -> JS, MXML -> JS, CSS -> JS, and .properties -> JS) has come up on another thread. I should mention that this approach is the one that the architect of the Falcon compiler (Chris Brichford, who recently left Adobe) recommended for getting to JS. Bernd Paradies, who did FalconJS, was on another team and decided to run with AS -> JS.
One advantage of ABC -> JS is that it solves the problem of having a 3rd party SWC that you don't have source code for but want to transcode to JS. One disadvantage is that you have to have a good understanding of the ABC format and its opcodes. - Gordon
