how to create staging server to test my app before deployment (node and nginx) and deploy it in production server in a single droplet?

I would make two instances of the copies of the app

For instance:

1. /var/www/app -> myapp.com
2. /var/www/staging -> staging.myapp.com

Then you can do your testing on the staging instance and once you are happy move the files over to the “production instance”.

thanks for replying. Could you please tell me how to do that? Thanks in advance.