Exposing B1 Service Layer through Node js Basic SAP Business One Service Layer proxy. SAP blog post: https://blogs.sap.com/2021/05/20/exposing-sap-business-one-service-layer-through-node-js/
You should create a .env file with:
SERVICELAYER="<SERVICE LAYER BASE URL>"
APIKEY="<YOUR SAP API HUB APIKEY>"
PORT="<PORT NUMBER>"