John,

This works for me in V12

a5w_report_saveAs(request.applicationRoot + e._currentRowDataNew.adminfactuurlayout+".a5rpt","pdf",filter,order,strfilename,global_variables(),printOptions,args,options)

if file.exists(strfilename)
Session.SaveDataAsFile(strFilenameuser,file.to_blob(strfilename))
jscmd = "window.open('"+Session.FormatFileDataURL(strFilenameuser)+"');"
end if

So look at a5w_report_saveAs
This is from a xbasic function returning javascript