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Complete JavaScript Course: Build a Real World App from Scratch

Responding to Requests

Explore how to build a simple JavaScript web server with the Express framework. Understand defining routes, handling HTTP requests, and setting your server to listen on a port to respond to browser queries.

We'll cover the following...

The main job of a web server is to respond to HTTP requests. Here’s the JavaScript code for a minimal Express-based web server that returns “Hello from Express!” for a request to the root URL.

Node.js
// Load the Express package as a module
const express = require("express");
// Access the exported service
const app = express();
// Return a string for requests to the root URL ("/")
app.get("/", (request, response) => {
  response.send("Hello from Express!");
});
// Start listening to incoming requests
// If process.env.PORT is not defined, port number 3000 is used
const listener = app.listen(process.env.PORT || 3000, () => {
  console.log(`Your app is listening on port ${listener.address().port}`);
});

You can launch your server with either node index.js or npm start, then type its root URL (http://localhost:3000 if your server runs on your local ...