mern-scaffold/applications/backend/index.js

mern-scaffold is a CLI tool that helps you to quickly develop basic boilerplate code for your MERN app. You can generate boilerplate code for your Frontend or Backend. You can also generate them as a full stack project.

// Require the 'dotenv' package which loads environment variables from a `.env` file into `process.env`.
require('dotenv').config();

// Require the 'express-async-errors' package which enables Express to handle errors thrown from asynchronous handlers.
require('express-async-errors');

// Require the 'express' package which is a Node.js web application framework.
const express = require('express');

// Require the 'cors' package which is a Node.js package for providing a Connect/Express middleware that enables CORS with various options.
const cors = require('cors');

// Require the 'morgan' package which is a Node.js HTTP request logger middleware for Node.js.
const morgan = require('morgan');

// Require the 'connectToDb' function from the 'config/db.js' file which connects to the database.
const { connectToDb } = require('./config/db');

// Require the 'errorHandler' middleware function from the 'middleware/errorHandler.js' file which handles errors.
const errorHandler = require('./middleware/errorHandler');

// Require the 'authRoutes' router from the 'routes/authRoutes.js' file which contains the authentication routes.
const authRoutes = require('./routes/authRoutes');

// Require the 'routeNotFound' middleware function from the 'middleware/noRouteFound.js' file which handles routes that are not found.
const routeNotFound = require('./middleware/noRouteFound');

// Create an instance of the Express application.
const app = express();

// Set the port number. If the environment variable `PORT` is set, use that value, otherwise use 3000.
const port = process.env.PORT || 3000;

// Use CORS middleware to enable cross-origin requests.
app.use(cors());

// Use Express's built-in JSON parsing middleware.
app.use(express.json());

// Use Morgan middleware for logging HTTP requests.
app.use(morgan('tiny'));

// Use the authentication routes.
app.use('/api/v1/auth', authRoutes);

// Use the route not found middleware.
app.use(routeNotFound);

// Use the error handler middleware.
app.use(errorHandler);

// Define the 'start' function which starts the server.
const start = async () => {
  try {
    // Connect to the database.
    await connectToDb();

    // Start listening on the specified port.
    app.listen(port, () => {
      console.log(`Listening on port ${port}`);
    });
  } catch (error) {
    // Handle any errors that occur while starting the server.
    console.log(error);
  }
};

// Call the 'start' function to start the server.
start();