Express - lesson 1 | HackIndia Skills

What you build

You will create the smallest useful backend for this track: one Express app with one route.

The route will answer GET / with JSON. This is the first proof that your API runs on your laptop and can later be shared in a public repo.

Key point

Remember this

An Express API is a Node app that listens for HTTP requests and sends responses.

A route connects one HTTP method and one path to one handler function. For example, GET / runs when someone opens the root URL.

Your to-do

Create the project

Do each one yourself, then tap it to tick it off. The ticks are only a checklist for you: they are not marked or scored.

Open a terminal in a new folder, such as recruiter-ready-api.
Check that you are using Node.js 24 LTS for this track.
Create a package.json file.
Install Express. Express 5 is the current latest line.
Create a src folder and an app.js file.

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node -v
npm init -y
npm install express
mkdir src

Example

First route

Put this in src/app.js.

This uses app.get('/', handler). The get part is the HTTP method. The '/' part is the path. Query strings are not part of the route path; you will handle them in a later lesson.

import express from 'express';

const app = express();
const port = 3000;

app.get('/', (req, res) => {
  res.json({
    message: 'Recruiter-ready API is running',
    owner: 'Your Name',
    status: 'ok'
  });
});

app.listen(port, () => {
  console.log(`API listening on http://localhost:${port}`);
});

Your to-do

Make imports work

Do each one yourself, then tap it to tick it off. The ticks are only a checklist for you: they are not marked or scored.

Open package.json.
Add type as module so Node accepts import syntax.
Add a dev script so you do not type the full command each time.

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{
  "type": "module",
  "scripts": {
    "dev": "node src/app.js"
  },
  "dependencies": {
    "express": "^5.2.1"
  }
}

Tip

Test like a user

Run npm run dev. Then open http://localhost:3000 in your browser.

You should see JSON, not an HTML page. This is normal for an API. Later, your frontend, Postman, curl, or a recruiter’s local machine can call the same route.

npm run dev

Common mistake

Avoid old syntax

Older tutorials may show Express 4 patterns. Do not copy response shortcuts like res.json(obj, status) or res.send(body, status).

In Express 5, set the status first when you need one: res.status(201).json(data). For today, the default 200 response is fine.

Your to-do

Do this now

Do each one yourself, then tap it to tick it off. The ticks are only a checklist for you: they are not marked or scored.

Create the folder and install Express.
Add src/app.js with the GET / route.
Add type and dev script in package.json.
Run npm run dev and open localhost:3000.
Change owner to your real name before you commit later.

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Ship Your First Express Route

What you build

Remember this

Create the project

First route

Make imports work

Test like a user

Avoid old syntax

Do this now

Quick check