Pop-up window, while file upload

[BenySay]

Hi ...

I have a scrip to upload an audio file to the server, How I can create a pop-up window to ask the user to wait until the upload is done?

I'm using the "copy" function to upload the file.

[Giacomo]

With JS, open popup on form submit, close it on target page load.

[BenySay]

Do you have an exemple of this code?