nginx is working, but, when doing proxy_pass, gives me: Cannot GET /nodejs

here are the lines I've added to nginx.conf

ProxyPass nodejs localhost:2345
ProxyPassReverse nodejs localhost:2345

2345 is where my node server is listening

I'm pointing chrome browser here:
http://localhost/nodejs

any ideas to fix it? web.js here is my node server:
http://plnkr.co/edit/ZdQqulPp4ovZqR9zikYm?p=preview

with apache ProxyPass[Reverse] this was working, but I'm trying nginx to see performance gains