One way to improve it might be to add a new JavaScript function into HTML which causes all further network access made by the current document to be blocked; th

One way to improve it might be to add a new JavaScript function into HTML which causes all further network access made by the current document to be blocked; the user who downloads the file can insert that command at the beginning of the file if they want to disable network access. (Since it is called before the rest of the document can change its definition, it will be effective.) (It is one of the many things which will need to be fixed in a newer web browser program, I think.)