You can use Apps Script which uses JavaScript along with Apps Script classes.
It depends on where the code is running from, who owns the Apps Script file and the permissions granted.
If Apps Script is running from your Google account then you won't need to use OAuth. All you need to use is the built-in DriveApp service.
If the code is running externally to the Google account with the folder, then you'd need to use the Google Drive API and OAuth.