How can I get Node.js to listen on port 80?

Hi! I followed the instructions here, https://www.digitalocean.com/community/articles/how-to-install-node-js-with-nvm-node-version-manager-on-a-vps, and I got a Node app up and running on port 3000. When I direct requests to that port, I see my app, but not when I send a request without specifying a port.

I tried running $ PORT=80 node app, and Node threw an error and quit. It worked when I used PORT=8080 though.

On IRC, @kamal_ suggested I install and configure NGINX to to serve the static files “and pass everything else to Node.js”, and now I have NGINX up and running. When I go to my droplet’s IP now, I see “Welcome to nginx!” instead of having the connection refused, but I still have to append :3000 to the URL to see my Node app.

This is the NGINX config file I got from @kamal_: https://p.kk7.me/mepayofuqo.nginx

What are the next steps to making the app load on requests to the default port?

Thanks in advance!