NestJS_Basic/catDataMocking/src/app.ts

import * as express from "express";
import * as cors from "cors";

import catsRouter from "./cats/cats.route";

const port: number = 8000;
class Server {
  public app: express.Application;

  constructor() {
    const app: express.Application = express();
    this.app = app;
  }

  private setRoute() {
    // * router
    this.app.use(catsRouter);
  }

  private setMiddleware() {
    this.app.use(cors());

    // * Logging Middleware
    this.app.use((req, res, next) => {
      console.log(req.rawHeaders[1]);
      next();
    });

    // * json middleware
    this.app.use(express.json());

    this.setRoute();

    // * 404 middleware
    this.app.use((req, res, next) => {
      console.log(req.rawHeaders[1]);
      console.log("This is 404 middleware");
      res.send({ error: "404 not found error" });
    });
  }

  public listen() {
    this.setMiddleware();
    this.app.listen(port, () => {
      console.log(`server is on ${port}`);
    });
  }
}

function init() {
  const server = new Server();
  server.listen();
}

init();