Sample server Express

app.js

const express = require("express");
const app = express();

// logger
const morgan = require("morgan");

const productRoutes = require("./api/routes/products");
const orderRoutes = require("./api/routes/orders");
// using the morgan the resul will beo nthe terminal
app.use(morgan("dev"));

// avoid Cross-Origin Request Blocked
app.use((req, res, next) => {
  res.header("Acces-Control-Allow-Origin", "*");
  res.header(
    "Acces-Control-Allow-Headers",
    "Origin",
    "X-Requested-With",
    "Content-Type",
    "Accept",
    "Authorization"
  );
  /**
   * ! Browsers is alwatys send an OPTION request first
   * ! when you send a POST request or PUT request
   */
  if ((req.method = "OPTIONS")) {
    /**
     * ! Addional header to tell the browser what it may send
     */
    res.header("Acces-Control-Allow-Methods", "PUT, POST, PATCH, DELETE, GET");
    return res.status(200).json({});
  }
  next();
});

// parsers
app.use(express.urlencoded({ extended: false }));
app.use(express.json());

app.use("/products", productRoutes);
app.use("/orders", orderRoutes);

/**
 * ! handling error for the whole application route or url request
 * ! it will fires if it did not find the fitting route
 */
app.use((req, res, next) => {
  const error = new Error("Not found");
  error.status = 404;
  next(error);
});

app.use((error, req, res, next) => {
  res.status(error.status || 500);
  res.json({
    error: {
      message: error.message
    }
  });
});

module.exports = app;

order.js

const express = require("express");
const router = express.Router();

router.get("/", (req, res) => {
  res.status(200).json({
    message: "Orders were fetched"
  });
});

router.post("/", (req, res) => {
  res.status(201).json({
    message: "Order was created"
  });
});

router.post("/:orderId", (req, res) => {
  res.status(200).json({
    message: "Order details",
    orerId: req.params.orderId
  });
});

router.delete("/:orderId", (req, res) => {
  res.status(200).json({
    message: "Order deleted",
    orerId: req.params.orderId
  });
});

module.exports = router;

products.js

const express = require("express");
const router = express.Router();

router.get("/", (req, res) => {
  res.status(200).json({
    message: "Handling GET request to /products"
  });
});

router.post("/", (req, res) => {
  res.status(200).json({
    message: "Handling POST request to /products"
  });
});

router.get("/:productid", (req, res) => {
  const id = req.params.productid;
  if (id === "special") {
    res.status(200).json({
      message: "You discovered the special ID",
      id: id
    });
  } else {
    res.status(200).json({
      message: "You passed an ID"
    });
  }
});

router.patch("/:productid", (req, res) => {
  res.status(200).json({
    message: "Updated product"
  });
});

router.delete("/:productid", (req, res) => {
  res.status(200).json({
    message: "Deleted product"
  });
});

module.exports = router;

server.js

const http = require("http");
const app = require("./app");

const port = process.env.PORT || 3000;

const server = http.createServer(app);

server.listen(port, () => {
  console.log(`Server running on port ${port}`);
});