Making simple apps in express

Simple Express app that serves as a landing page with a form that allows users to submit their email addresses:

Copy codeconst express = require('express');
const app = express();
const bodyParser = require('body-parser');
const MongoClient = require('mongodb').MongoClient;

// serve static files from the 'public' directory
app.use(express.static('public'));

// use body-parser to parse form data
app.use(bodyParser.urlencoded({ extended: true }));

// connect to the database
MongoClient.connect('mongodb://localhost:27017/mydatabase', (err, client) => {
  if (err) {
    console.log(err);
    return;
  }
  console.log('Connected to database');
  const db = client.db('mydatabase');

  // set the view engine to ejs
  app.set('view engine', 'ejs');

  // render the landing page with the email form
  app.get('/', (req, res) => {
    res.render('index.ejs');
  });

  // handle form submission
  app.post('/submit-email', (req, res) => {
    const email = req.body.email;
    console.log(`Received email: ${email}`);
    // save the email to the database
    db.collection('emails').insertOne({
      email: email
    }, (err, result) => {
      if (err) {
        console.log(err);
        return;
      }
      console.log(`Saved email to database: ${email}`);
      // redirect back to the landing page
      res.redirect('/');
    });
  });

  // start the server
  app.listen(3000, () => {
    console.log('Express app listening on port 3000');
  });
});

To run this app, you must have installed Node.js, Express, body-parser, and MongoDB. Here's how you can install and run the app:

Make sure you have Node.js installed. If you don't have it installed, you can download the latest version from the official website: nodejs.org
Install MongoDB by following the instructions on the official website: docs.mongodb.com/manual/installation
Please create a new directory for your app and navigate to it in your terminal.
Run the following command to install Express and body-parser:

npm install express body-parser

Create a file called app.js in your directory and paste the code above into it.
Create a directory called public and create a file called index.ejs inside it. This file will contain the HTML for your landing page. Here's an example of what it could look like:

Copy code<!DOCTYPE html>
<html>
  <head>
    <title>Landing Page</title>
    <link rel="stylesheet" href="/css/style.css">
  </head>
  <body>
    <h1>Welcome to our landing page</h1>
    <form action="/submit-email" method="