javascript-today

Setting Up NodeJS

Getting started with NodeJS is straightforward. This tutorial will walk you through installation, verification, and running your first Node script.

Installing NodeJS

Option 1: Download from Official Website (Easiest)

  1. Visit nodejs.org
  2. Download the LTS version (Long Term Support)
    • More stable for production use
    • Gets security updates for longer
  3. Run the installer and follow the prompts
  4. Restart your terminal/command prompt

On Mac/Linux (using nvm):

# Install nvm
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.0/install.sh | bash

# Install latest LTS
nvm install --lts

# Use it
nvm use --lts

On Windows (using nvm-windows):

# Download from github.com/coreybutler/nvm-windows
# Then install specific version:
nvm install 20.10.0
nvm use 20.10.0

Why use a version manager?

  • Easily switch between Node versions
  • Test your code on different versions
  • Avoid permission issues

Verify Installation

After installing, verify it worked:

# Check Node version
node --version
# Should output something like: v20.10.0

# Check npm version (comes with Node)
npm --version
# Should output something like: 10.2.3

Your First Node Script

1. Create a JavaScript file

Create a file called hello.js:

// hello.js
console.log("Hello from NodeJS!");
console.log("Node version:", process.version);
console.log("Platform:", process.platform);

2. Run it with Node

node hello.js

Output:

Hello from NodeJS!
Node version: v20.10.0
Platform: darwin

The Node REPL

REPL stands for Read-Eval-Print-Loop. It’s an interactive JavaScript environment:

# Start REPL
node

# Now you can type JavaScript:
> 5 + 3
8
> const name = "Alice"
undefined
> `Hello ${name}!`
'Hello Alice!'
> .exit  // or Ctrl+C twice

This is great for:

  • Testing code snippets
  • Learning JavaScript syntax
  • Quick calculations
  • Experimenting with Node APIs

Node Global Objects

NodeJS provides several global objects (available everywhere):

// Process information
console.log(process.version);  // Node version
console.log(process.cwd());    // Current working directory
console.log(process.env);      // Environment variables

// Timers (same as browser)
setTimeout(() => console.log("Later!"), 1000);
setInterval(() => console.log("Tick"), 1000);

// File path info
console.log(__filename);  // Current file path
console.log(__dirname);   // Current directory path

Running Scripts with Arguments

You can pass arguments to your Node scripts:

// args.js
console.log("Arguments:", process.argv);

// First two are always:
// [0] = path to node executable
// [1] = path to script file
// [2+] = your arguments

const userArgs = process.argv.slice(2);
console.log("User arguments:", userArgs);

Run it:

node args.js hello world 123

Output:

Arguments: ['/usr/local/bin/node', '/path/to/args.js', 'hello', 'world', '123']
User arguments: ['hello', 'world', '123']

Common Node Commands

# Run a script
node script.js

# Run with environment variable
NODE_ENV=production node server.js

# Check Node version
node --version

# Check npm version
npm --version

# Start interactive REPL
node

# Run script and watch for changes (requires nodemon)
npx nodemon script.js

Next Steps

Now that you have NodeJS installed, you’ll learn about:

  • How modules work in Node
  • Using npm to install packages
  • Working with the file system
  • Creating web servers