How to fetch file object of vaulted File with JS so we can later read the file content?

Hi community,

does anybody a way to read the file content of existing Files in the Vault (mainly xml data) with Javascript?

For example we have an CAD item with an xml file in the property native_file.  With an button click I want to read the filecontent and stream the result to another system. (I know that the xml files are not the typical content of the CAD ItemType, I just abuse this ItemType for my current test :-) ). 

I know that we can use fetchFileProperty to download files to the client. In addition there seems to be an additional 3rd parameter where we can define if we really want to download the file (Standard Mode), or only get the File item (Dry Mode). But none of these two modes will return the native FileObject needed for the FileReader.

I tried the following code from a regular Form button:

var fileObject = document.thisItem.fetchFileProperty("native_file", "C:\\Temp", 1);

This variant will return the file item. Is there any way to get the file object itself with JS?

Another possible solution would be to use C# for this task. This way we could download the file temporary to the server and then ready the file content there. But maybe it´s possible to avoid this additional download?

Thanks for any help!