npm & package.json

npm is the default package manager for Node.js, and package.json is the manifest file at the root of every project that records its name, version, scripts, and the third-party dependencies npm installs.

Learn npm & package.json in our free Node.js course — a beginner-friendly interactive lesson with worked examples, a practice exercise and a quick reference.

Part of the free Node.js course at LearnCodingFast — hands-on lessons with examples you run in your browser, plus practice exercises and a quick quiz.

By the end of this lesson you'll create a package.json with a single command, install both runtime and development packages, understand semver ranges, and define npm scripts that turn long commands into short, memorable names.

What You'll Learn in This Lesson

1️⃣ Creating a Manifest with npm init

Every Node.js project starts with a package.json file. You could write it by hand, but npm will scaffold one for you. Running npm init asks a series of questions; adding the -y ("yes") flag accepts all the defaults instantly.

That file is the heart of your project. Here is an annotated example showing the fields you'll meet most often. The name , version , and main fields describe the package itself; scripts and the two dependency objects do the day-to-day work.

2️⃣ Installing Packages

The whole point of npm is reusing code other people wrote. The npm install command (short: npm i ) downloads a package and records it in your package.json . Where it gets recorded depends on the flag you use.

When npm writes a dependency, it usually adds a version range rather than a single exact version, so you can pick up small bug fixes automatically. Those ranges use semantic versioning ( MAJOR.MINOR.PATCH ) with two key symbols:

3️⃣ npm Scripts

Typing long commands gets old fast. The "scripts" object lets you give a command a short name, then run it with npm run <name> . This is how almost every Node project standardises how it's started, developed, and tested.

A few script names are special: start and test can be run without the word run . Every other script needs npm run in front of it.

Your turn. Fill in the three blanks marked ___ to build a working manifest, then save it as package.json and run npm start .

No blanks this time — just a brief and an outline. Run the steps yourself in an empty folder and confirm the result against the expected file tree. This sequence is exactly how a real Node project begins.

📋 Quick Reference — npm Commands

Tip: the "scripts" object lives inside package.json as {' '} .

Practice quiz

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