Export documents inside an InDesign book in a single PDF file

I have several documents inside an InDesign book. Is there a way that they can be exported into one single PDF file?

Here is the script I am using:

    for (var i = 0; i < data.chapters.length; i++)
       {
            show_list.children[0].selection = i; show_list.show ();
            
            DocName = data.chapters.name;
           
            app.open (data.chapters, false);
            
            f = new File (data.chapters.fullName.replace (/indd$/, "pdf"));

            app.pdfExportPreferences.pageRange = PageRange.allPages;
            app.documents.itemByName(DocName).exportFile(ExportFormat.pdfType, f, false, data.preset);
            app.documents.itemByName(DocName).close(SaveOptions.no);
       }

The script exports them to PDF but each document is a separate PDF file.

Any hep would be appreciated.  Thanks.