CharacterStyles of a document inside an InDesign book

Question

How do I list the characterStyles of a document that is inside a book without opening the document?  This is my script:
    app.open (book_contents[0], false);
    var charStylesDD =app.documents.item(0).characterStyles.everyItem().name;
    app.documents.item(0).close (SaveOptions.no);     
It works but this happens before a window is opened, as you might imagine it may take a long time and users might think the script did not run.  If I remove the app.open part, the value of charStylesDD is undefined.
I need something like:
book.bookContents.everyItem().characterStyles.everyItem.name;
But unfortunately book.bookContents does not have the characteStyles function.
Any help would be appreciated.  Thanks guys! 

Answer 1

No, Javascript doesn't allow access to the raw file. You absolutely need to open it first in InDesign.