Node.js: Installation and Setup

Last updated: 2026-08-26

Bob is a front-end developer who just started working at a tech company. On his first day, his mentor gave him the project repository URL. After cloning it, he ran npm install but got a bunch of errors—it turned out the company’s project was using Node.js 22 LTS, while he was still running the older version 18 on his local machine. Bob was caught in a dilemma because he was worried that upgrading directly might affect other legacy projects. Fortunately, his mentor recommended nvm, which allowed him to switch freely between different Node.js versions, ensuring each project used its own compatible version without interfering with the others. From then on, Bob never had to worry about version conflicts again.

What You'll Learn

• Installing and Switching Between Node.js Versions Using nvm
• Verify that Node.js and npm have been installed successfully
• Execute JavaScript code in the REPL interactive environment
• Write and run your first Node.js script
• Use npm init to create a package.json project configuration file

1. Installing and Using nvm

(1) Why do we need nvm?

Node.js is updated frequently, and different projects may depend on different versions. nvm (Node Version Manager) allows you to install multiple versions of Node.js on the same machine and switch between them as needed, thereby avoiding version conflicts.

(2) Install nvm

macOS / Linux:

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.1/install.sh | bash

Once the installation is complete, restart the terminal or run the following command:

source ~/.bashrc

Windows：

Windows users can use nvm-windows. After downloading the installer, follow the wizard to complete the installation.

▶ Example: (3) Installing and Switching Between Node.js Versions

nvm install 22
nvm use 22
nvm alias default 22

▶ Example: Installing Node.js 22 LTS and Switching

$ nvm install 22
Downloading and installing node v22.11.0...
Now using node v22.11.0 (npm v10.9.0)

$ nvm use 22
Now using node v22.11.0 (npm v10.9.0)

$ nvm current
v22.11.0

(4) Comparison of Node.js Installation Methods

2. Verifying the Node.js Installation

(1) Check the Node.js version

Once the installation is complete, open the terminal and enter:

node --version

If the output looks like v22.11.0, it means Node.js has been installed correctly.

(2) Check the npm version

npm is installed along with Node.js. To verify this:

npm --version

If the output looks like 10.9.0, it means npm is available.

▶ Example: Complete Verification Process

$ node --version
v22.11.0

$ npm --version
10.9.0

$ node -e "console.log('Node.js is working!')"
Node.js is working!

Tip: node -e allows you to execute a single line of JavaScript code directly, which is useful for quick testing.

3. REPL Interactive Environment

(1) Entering and Exiting the REPL

Type node in the terminal to enter the REPL (Read-Eval-Print Loop) interactive environment:

node

To exit: Enter .exit or press Ctrl + C twice.

(2) Common REPL Commands

(3) Multi-line Input

REPL automatically detects unclosed parentheses and curly braces and enters multi-line input mode:

> function add(a, b) {
...   return a + b;
... }
undefined
> add(3, 5)
8

▶ Example: Quickly testing code in the REPL

> const prices = [9.99, 24.5, 3.75, 18.0]
undefined
> prices.filter(p => p > 10).reduce((sum, p) => sum + p, 0)
42.5
> const total = prices.reduce((sum, p) => sum + p, 0)
undefined
> total
56.24

4. Run Your First Script

(1) Create a JavaScript file

Create a new file named hello.js:

const greeting = 'Hello, Node.js!';
console.log(greeting);

const version = process.version;
console.log(`Running on ${version}`);

▶ Example: (2) Run using the node command

node hello.js

▶ Example: Running a script and passing parameters

Created by greet.js:

const name = process.argv[2] || 'World';
console.log(`Hello, ${name}!`);
console.log(`Node version: ${process.version}`);
console.log(`Current directory: ${process.cwd()}`);

Execute:

$ node greet.js Bob
Hello, Bob!
Node version: v22.11.0
Current directory: /home/bob/projects/demo

(3) Introduction to the process Object

process is a global object in Node.js that can be used without require. Common properties:

5. Creating package.json

▶ Example: (1) Create interactively using npm init

npm init

npm will prompt you for information such as the project name, version, and description one by one, and will ultimately generate package.json.

▶ Example: (2) Use npm init -y to quickly create a project

npm init -y

-y Skips all questions and generates package.json using default values, making it ideal for a quick start.

▶ Example: package.json generated by npm init -y

$ mkdir my-app && cd my-app
$ npm init -y

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

(3) Description of Key Fields in package.json

(4) Semantic version range notation

6. Common Development Tools

(1) Installing and Configuring VS Code

VS Code is the most popular editor for Node.js development, with a built-in terminal and debugger.

(2) Recommended Node.js Extensions

(3) VS Code's Built-in Terminal

Use the keyboard shortcut Ctrl + to open the built-in terminal, so you don't have to switch between the editor and the terminal.

▶ Example: Configuring VS Code to Debug Node.js

Create .vscode/launch.json in the project root directory:

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "node",
      "request": "launch",
      "name": "Launch Program",
      "skipFiles": ["<node_internals>/**"],
      "program": "${workspaceFolder}/index.js"
    }
  ]
}

Press F5 to start debugging.

7. The Process of Managing Multiple Versions of Node.js with nvm

flowchart TD
    A[Installation nvm] --> B[nvm install 22]
    B --> C[nvm install 18]
    C --> D[nvm use 22]
    D --> E{Project Switching?}
    E -->|Enter the Project A| F[nvm use 22]
    E -->|Enter the Project B| G[nvm use 18]
    F --> H[node --version Verification]
    G --> H
    H --> I[Run Project]
    I --> E

flowchart TD
    A[Installation nvm] --> B[nvm install 22]
    B --> C[nvm install 18]
    C --> D[nvm use 22]
    D --> E{Project Switching?}
    E -->|Enter the Project A| F[nvm use 22]
    E -->|Enter the Project B| G[nvm use 18]
    F --> H[node --version Verification]
    G --> H
    H --> I[Run Project]
    I --> E

8. Comprehensive Example: Creating a Node.js Project from Scratch

The following walkthrough demonstrates the entire process, from installing Node.js to running your first script:

# 1. Install and switch to Node.js 22 LTS
nvm install 22
nvm use 22

# 2. Verify the Installation
node --version
npm --version

v22.11.0
10.9.0

# 3. Create a project directory and initialize it
mkdir bob-project
cd bob-project
npm init -y

Created by index.js:

const projectName = require('./package.json').name;
const version = process.version;

console.log(`Project: ${projectName}`);
console.log(`Node.js: ${version}`);
console.log(`Directory: ${process.cwd()}`);

const item = ['setup', 'config', 'deploy'];
item.forEach((item, index) => {
  console.log(`Step ${index + 1}: ${item}`);
});

Running Projects:

node index.js

Project: bob-project
Node.js: v22.11.0
Directory: /home/bob/bob-project
Step 1: setup
Step 2: config
Step 3: deploy

❓ FAQ

📖 Summary

• nvm is the preferred tool for managing multiple versions of Node.js; it supports installing, switching between, and setting the default version
• node --version and npm --version are used to verify whether the installation was successful
• REPL provides an interactive execution environment, ideal for quickly testing code snippets
• Use node <file> to run a JavaScript script, and process.argv to retrieve command-line arguments
• npm init -y Quickly create a package.json file—this is the first step in initializing a project
• VS Code + Node.js extensions are the most popular combination of development tools

📝 Exercises

1. Install Node.js 22 LTS using nvm and set it as the default version
2. Enter the REPL, define a function that calculates the sum of all even numbers in an array, and verify the result
3. Create a project directory, initialize it using npm init -y, and then modify the name and description fields in package.json
4. Write a script info.js that outputs the current Node.js version, the operating system platform (process.platform), and the runtime (process.uptime()).
5. Install the Node.js Extension Pack in VS Code, configure launch.json, and successfully debug and run a script

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