This is an example Node.js systemd service for Raspberry Pi. This repository is used in a Medium article that describes how to use systemd with Node.js on the Pi.
Clone the repo, cd to the folder containing the cloned files, then:
export PORT=8888
npm start
Browse to http://127.0.0.1:8888 or curl 127.0.0.1:8888 to see the current timestamp.
Instructions on how to install this as a systemd service using the timestamp.service file in this repo can be found in my Medium article.