What library/API or even a program for converting flash code into html 5 code automatically do you recommend me? thank you very much
Given that Gordon is a flash runtime written in JS, it seems like it would be possible to create a version that compiles flash to JS based on the same code. Not trivial, but doable, and a lot of the hard work is already done.
A couple of notes - beware of the browser compatibility issues and swf tag support in Gordon currently, and target accordingly.
Edit (thanks naikus!): Looks like (as was inevitable) work has already started on a flash to JS compiler called Smokescreen. It is supposed to be open-source, but for now I only see demos, so we'll still to wait for the complete deal (though I suppose you could perhaps dig around their js code for tips/etc in the meantime).