npm & Your First Package

By the end of this lesson you will be able to:

1. Create a package.json in a new folder with npm init -y.
2. Install a package with npm install and find it inside node_modules.
3. Use an installed package in a .js file with require() and run it with Node.
4. Add an npm script and run it with npm run or npm start.

Last lesson you ran a .js file from the terminal with node. Today every project keeps a small settings file called package.json. Here is a tiny one:

{
  "name": "kuih-shop",
  "scripts": {
    "start": "node index.js"
  }
}

Predict together

• What single command does npm start actually run?
• If the file were named app.js instead, what would you change?

Think of your phone. When you want a new feature, you do not build the app — you open the app store and install one. npm is exactly that, but for code. It is the Node Package Manager: an enormous shop of ready-made code called packages that anyone can install.

Every project you install packages into needs a package.json — think of it as the project's shopping list and ID card in one. It records the project's name, its version, and every package it depends on.

Making a package.json

You do not write it by hand. Inside your project folder, run this in the terminal:

$ npm init -y

The -y means “say yes to every question”, so npm fills in sensible defaults and writes this file for you:

{
  "name": "my-project",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}

The fields that matter to you today:

When you install a package, its code lands in a folder called node_modules. That folder can hold thousands of files, so we never share it — it is listed in .gitignore and left out of Git. Anyone with your package.json can rebuild it with one command: npm install.

Why it matters

Real backends stand on hundreds of packages: web servers, date helpers, password tools. npm is how every one of them arrives. Learn npm now, and the rest of Level 3 — Express, Postgres tools, and more — installs the same way.

Follow along on your own machine. Open the VS Code terminal with Terminal → New Terminal. We will build a tiny project that prints today's date in a friendly format.

Step 1 — Make a folder and start the project

Create a folder, move into it, then let npm set it up:

$ mkdir date-printer
$ cd date-printer
$ npm init -y

npm confirms it wrote the file:

Wrote to /date-printer/package.json:

{
  "name": "date-printer",
  "version": "1.0.0",
  ...
}

Step 2 — Look at package.json

Open package.json in VS Code. Notice the name is date-printer and there is no dependencies field yet — you have not installed anything. That is about to change.

Step 3 — Install a package

dayjs is a tiny package for working with dates. Install it:

$ npm install dayjs

added 1 package in 2s

Two things changed. A node_modules folder appeared, and your package.json now has a dependencies field:

"dependencies": {
  "dayjs": "^1.11.13"
}

Step 4 — Use it in a file

Make a file called index.js. The require() function pulls an installed package into your code:

const dayjs = require('dayjs')

const today = dayjs().format('dddd, D MMMM YYYY')
console.log('Selamat datang! Today is ' + today)

Run it with Node:

$ node index.js

Selamat datang! Today is Saturday, 4 July 2026

Step 5 — Add a start script

Typing node index.js every time is a chore. Open package.json and add a start line inside scripts:

"scripts": {
  "start": "node index.js"
}

Now run the whole thing with a shorter command:

$ npm start

Selamat datang! Today is Saturday, 4 July 2026

What changed? You went from writing every line yourself to borrowing dayjs from npm, then gave your run command a nickname. Same result, far less typing.

Keep working in your date-printer folder. Run scripts with npm run <name> and files with node index.js.

1. Task 1 — Add your own script

   In package.json, add a second script named hello next to start:

   "scripts": {
     "start": "node index.js",
     "hello": "node index.js"
   }

   Save, then run it with npm run hello. Notice that start is special (npm start works), but your own scripts always need the word run.

2. Task 2 — Install one more package

   Install the tiny package chalk with npm install chalk@4. It colours terminal text. Use it in index.js:

   const chalk = require('chalk')
   console.log(chalk.green('Today looks bright, Aisyah!'))

   Run it and check the message prints in green.

3. Task 3 — Fill in the ID card

   Open package.json. Change name to something of your own (lower-case, no spaces), bump version to 1.1.0, and add a real description line that says what your project does. Save and check npm start still runs.

Build a small project called countdown that uses dayjs to print how many days are left until a Malaysian holiday. dayjs has a .diff() method that counts the gap between two dates. Combine it with what you know from Level 2 about printing text.

It works if: running node index.js (or npm start) prints a single line with a whole number of days.

// index.js — days until Hari Raya for Faiz
const dayjs = require('dayjs')

const hariRaya = dayjs('2027-03-20')
const daysLeft = hariRaya.diff(dayjs(), 'day')

console.log('Only ' + daysLeft + ' days until Hari Raya!')

Only 259 days until Hari Raya!

• npm — the Node package manager — is a huge shop of ready-made code.
• npm init -y creates a package.json: your project's ID card and shopping list.
• npm install <package> copies code into node_modules and lists it under dependencies.
• Bring a package into a file with require('<package>'), then run it with Node.
• An npm script is a command nickname — run it with npm run <name>, or npm start for start.

New words

• npm — the Node Package Manager: the tool that installs packages.
• package.json — the file that describes your project and its packages.
• node_modules — the folder where installed package code lives (kept out of Git).
• Dependency — a package your project needs to run.
• Script — a named command shortcut inside package.json.