Basic local web server running on port 3000

app.js

const PORT_NUMBER = 3000;

// Requiring express for routing                                                                                                                                                                                        
const express = require('express');

// Creating app from express                                                                                                                                                                                            
const app = express();

// Requiring in-built file system                                                                                                                                                                                       
const fs = require('fs');

// GET request to the root of the app                                                                                                                                                                                   
app.get('/', function(req, res) {
  res.sendFile(__dirname + '/index.html');
})

// Creating server at port 3000 (PORT_NUMBER)                                                                                                                                                                           
app.listen(PORT_NUMBER, function(req, res) {
  console.log(`Server started on port ${PORT_NUMBER}; visit http://localhost:${PORT_NUMBER}`);
})

Make sure that index.html is in the same directory, and then run node app.js (assuming Nodejs is installed).