Lab · Backend Development

Lab: your first Express server

Labbeginner· about 2 hours· 5 steps

The brief

Install Node.js and Express on your own computer and build the Kirana API: a health check, a product lookup with a path parameter and a 404, and a POST that reads JSON and answers 201. You test each part with curl, the way backend developers do.

Why it matters

Node.js with Express runs the backends of thousands of Indian startups and agencies. Every backend job starts with this loop: write a route, start the server, hit it with curl or Postman, read the status and the JSON. Being fast at it is the most basic backend skill.

Skills you practise

node and npm
npm init and npm install
express(), app.get and app.post
req.params and res.status
express.json() middleware
environment variables (PORT)
testing with curl

You need

Node.js 20 or newer (the LTS version from nodejs.org)
A terminal: Terminal on macOS/Linux, or PowerShell on Windows 10/11 (type curl.exe there, because curl is a different command in PowerShell)
VS Code or any code editor

What you will have at the end

A kirana-api folder with package.json and server.js: a running Express API with a health check, a lookup with 404 and a validated POST.

How it is marked (rubric, 100 points)

Everything runsEvery pasted output passes and the checklists are honestly ticked.	45
Right status codes200 for reads, 201 with Location for creates, 400 for bad input, 404 for missing items.	20
Good habitsPORT from the environment, node_modules ignored, input validated before it is stored.	20
Can explainYou can explain what middleware is and why express.json() must come before the routes.	15

0/5 steps done

Step 1 of 5

Check Node.js and npm

node -v shows version 20 or newer, and npm -v shows a version number.

Node.js runs JavaScript outside the browser, and npm installs packages like Express. Install the LTS (long-term support) version from nodejs.org; it is the one companies use. Older versions such as 16 and 18 no longer get security fixes, and new packages refuse to install on them.

Run this on your machine, then paste the output below

$ node -v; npm -v

Your notes: server.js

Write down each command you ran. It goes into your project summary.