minimal example of API using expressjs. Demo: https://youtu.be/0Tj7u-8Iav0

api.js

const express = require("express");
const app = express();
const router = express.Router();
app.use(express.json());

const port = 3000;

// Start server
app.listen(port, () => {
    console.log("Server running on port %PORT%".replace("%PORT%",port))
});
 
// Insert here other API endpoints
/*
GET Requests
/
/one

POST Requests
/two

*/
// Root endpoint
app.get("/", (req, res, next) => {
  res.send("API end points include /one, /two");
});

// the `/one` endpoint showing hard coded json object
app.get("/one", (req, res, next) => {
  res.status(200).json({"name": "one"});
});

// the `/two` endpoint 
app.post("/two", (req, res) => {
  res.status(200).json(req.body);
});

// Default response for any other request
app.use(function(req, res){
    res.status(404);
});

makefile

default:
	node api.js
  
install:
	npm install express