I modelled a surface in a CAD program, gave it a certain name (e.g. surface1) and locally saved this surface with a specific name on my desktop (e.g. filename = surf or apple or ...).

Now I write an application where I want to upload/post a larger number of such surf-files on a website. Via a SaveFileDialog I can choose the required files and upload them.

The files are imported as follows: var filename = dialog.showOpenDialog(options);

The files are served for the public webserver as follows:

[...]
.then(async function (data) {
            token = data.id_token;
            let formData = new FormData;
            formData.append('file', new Blob([fs.readFileSync(filename.toString())]), filename.toString().split("/").pop());
            let response = await fetch(url, {
                method: 'POST',
                headers: {
                    "Accept": "application/json, text/plain, */*",
                    "Authorization": " Bearer " + token
                },
                body: formData
            });
            return response;

The problem: For some filter routine I need the original object or surface name, like it was chosen in the CAD program (surface1). When I want to work with the variable filename, the SaveFileDialog only seems to take the local file path with the freely chosen desktop name (surf). The original object name (surface1) seems to be overwritten for a further use in my application.
But when I upload the file manually on the website (Frontend), the user interface shows me the original object or surface name like in the CAD program (surface1).

(Interesting fact: The code above also results in a successful post/upload with the original object name on the user interface (surface1). But when I try to pull the name from filename.toString().split("/").pop() I get the desktop name (surf) again.)

Where could the webserver get the original object name from? How can I get the original name of the object (surface1)?

Don't hesitate to ask for more infos if I was to restrained. The framework I use is Electron. Thank you!