I wouldn't like to say its im/possible… But closer to not worth the bother…
If you have received a script in jsxbin format, the author didn't want you to see the source code. While Muppet Mark is right (it surely is "possible"), attempting to get the source anyway sounds like a breach of trust.
If you want a modification of the original script, you could always ask the author.
How to get it closer?
What they are trying to say is that jsxbin is a binary format and not meant to decode.
Find some other way to solve your problem.