We are looking for a JSX script that can save a copy of the INDB as an IDML after save. The .indb is the main book document in Adobe InDesign CS5/6. The code would be roughly similar to the one below for INDD to IDML but in our case specific for the .indb book document itself. Other persons have asked this same question in recent years (on Adobe forums).
In Adobe InDesign scripting, there isn't a direct way to access individual documents within a book file and export them to IDML automatically.
To achieve the task of converting individual documents within a book file to IDML, you would need a more complex script that programmatically opens each document, exports it to IDML, and then closes it. Here's Indesign script that you can use for this purpose: