With systemd creating a service is almost trivial; no scripting involved! A sample script that I wrote for my test service looks like this:
[Unit]
Description=Verdaccio
[Service]
User=pi
WorkingDirectory=/home/pi/verdaccio
ExecStart=/home/pi/verdaccio/node_modules/.bin/verdaccio
[Install]
WantedBy=multi-user.target
The file should be saved (for example) in /lib/systemd/system/yourservicename.service. Starting and stopping the service will be:
$sudo service yourservicename start
$sudo service yourservicename stop
To register/ deregister a service to autostart:
$sudo systemctl enable yourservicename
$sudo systemctl disable yourservicename