How a Request Moves Through a Simple Node App

Last year, I picked up Node.js. I was excited, building tiny apps, exploring Express, thinking I was finally getting the hang of backend stuff. Then… I didn’t touch it for months. Life happened.

When I resumed, I realized something funny: I could still write code that “worked”, but I couldn’t explain what actually happened when a request hit my server. Even something as simple as GET/users felt a little magical. That’s when I decided to slow down and trace a request from start to finish.

Following a request

To make sense of it, I decided to follow a request through a Node app step by step. Here’s what I mapped out:

1. The client sends a request - for example, a browser asking for GET/users

2. Node receives it - the server picks up the request and starts looking for middleware or route handlers

3. Middleware runs - in my tiny test app, I just had a logger that prints “Request received”. Middleware can also transform or block requests

4. Route handler executes - Express finds a matching route and generates a response

5. Response goes back to the client - the browser finally gets the data or page it requested

6. Request lifecycle ends - everything resets, and Node waits for the next request

It’s very straightforward, but seeing it all together made everything click.

A tiny Node app for clarity

Here’s the minimal setup I used while retracing the flow:

const express = require('express')
const app = express()

// Middleware logs each request
app.use((req, res, next) => {
    console.log('Request received');
});

// Route handler responds to /users
app.get('/users', (req, res) => {
    res.send('User list');
});

// Start the server
app.listen(3000, () => {
    console.log('Server is running on port 3000');
})

Noting fancy. One file, one route, one piece of middleware. But tracing a single request through this tiny app helped me understand the path every request takes.

Why this mattered

Coming back to Node after months of not touching it was humbling. I realized I wasn’t starting from scratch; I just needed to slow down and see the flow.

There’s still so much I’m figuring out, and I’ll be sharing each little discovery here on CodeWithKay

#NodeNuggets #CodeWithKay