Install Node.js and Run Your First Script

You can install Node.js by downloading an installer from the website, but that is not what most working developers do. They use a version manager instead. This post walks through the setup that scales — install once, switch versions per project, never fight your system again.

If you have never seen Node before, start with What Is Node.js? for the background.

Why a version manager

Different projects need different Node versions. A legacy service might be locked to Node 18; a new project might target Node 22. The installer from nodejs.org puts a single version on your system, and upgrading or downgrading is a chore.

A version manager solves this. You install many Node versions side by side, and switch between them with a single command. The tool of choice on macOS and Linux is nvm (Node Version Manager). On Windows, nvm-windows does the same job.

Install on macOS or Linux

Open a terminal and run the official install script:

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.7/install.sh | bash

The script adds a few lines to your shell config (~/.zshrc on modern macOS, ~/.bashrc on most Linux distros). Close and reopen your terminal, or source the file:

source ~/.zshrc
# or
source ~/.bashrc

Confirm nvm is on your path:

command -v nvm
# output: nvm

If you see nvm, you are ready. If you see nothing, your shell config did not load the install snippet — open the file and check that the NVM_DIR lines exist near the bottom.

Install on Windows

nvm itself does not support Windows. Use nvm-windows instead — a separate project with similar commands.

1. Visit github.com/coreybutler/nvm-windows/releases
2. Download nvm-setup.exe from the latest release
3. Run the installer and accept the defaults
4. Open a new PowerShell or Command Prompt window

Verify the install:

nvm version
# output: 1.1.12

From here, the commands are nearly identical to nvm on macOS/Linux.

Install Node itself

With nvm installed, pick the latest LTS release. LTS (Long Term Support) versions get security patches for thirty months — exactly what you want for real work.

nvm install --lts

nvm downloads the release, installs it, and sets it as the active version. Test it:

node --version
# output: v22.11.0

npm --version
# output: 10.9.0

npm ships with Node, so you get it for free.

To install a specific version:

nvm install 20
nvm install 18.19.0

And to switch between installed versions:

nvm use 20
node --version
# output: v20.18.0

nvm use --lts
node --version
# output: v22.11.0

Pin a version per project

Drop a .nvmrc file at the root of any project:

echo "22" > .nvmrc

Then nvm use inside that directory will read the file and switch automatically:

nvm use
# output: Now using node v22.11.0

Commit .nvmrc to your repo. Anyone who clones it gets the right version with one command.

Run your first script

Create a file called hello.js in any folder:

// hello.js
const name = 'world';
console.log(`Hello, ${name}!`);

Open a terminal in that folder and run it:

node hello.js
# output: Hello, world!

That is the whole workflow. Edit, save, run. No build step, no configuration, no boilerplate.

Try a slightly bigger script — one that actually does something useful:

// sum.js
const numbers = process.argv.slice(2).map(Number);
const total = numbers.reduce((acc, n) => acc + n, 0);
console.log(`Sum of ${numbers.join(', ')} is ${total}`);

Run it with arguments:

node sum.js 3 4 5
# output: Sum of 3, 4, 5 is 12

process.argv is the array of command-line arguments. The first two entries are the path to Node and the path to your script — that is why we slice(2).

The REPL

A REPL — Read-Eval-Print Loop — is an interactive prompt for trying things out. Type node with no arguments:

node

You will see a > prompt. Type any JavaScript expression and press Enter:

> 2 + 2
4
> const greet = (name) => `hi, ${name}`
undefined
> greet('Yash')
'hi, Yash'
> [1, 2, 3].map(n => n * n)
[ 1, 4, 9 ]

The REPL is perfect for exploring an API quickly. Want to see what Object.keys does on a date? Try it. Want to test a regex? Type it. No file to create, no script to run.

Press Ctrl+D (or .exit) to leave the REPL.

A few REPL conveniences:

• Tab completion — type Array. and hit Tab to see every available method.
• History — Up/Down arrows step through previous lines, even across sessions.
• _ variable — holds the result of the last expression. Useful for chaining.

> 10 * 10
100
> _ + 1
101

Running TypeScript or modern JS

If you want to run TypeScript directly, modern Node has built-in stripping in v22.6+:

node --experimental-strip-types script.ts

For older versions or full type checking, tsx is the popular tool:

npm install -g tsx
tsx script.ts

You do not need any of this to get started. Plain .js files run as-is.

Common problems

command not found: node — your shell did not pick up nvm. Close the terminal completely and reopen it. If that still fails, check that your shell config (~/.zshrc or ~/.bashrc) has the NVM_DIR block at the bottom.

nvm: command not found after install — the install script edits your shell rc file. If you use a non-standard shell (fish, nushell), you may need to add the snippet manually. The nvm README has instructions.

Permission errors when installing global packages — never use sudo npm install -g. If you see EACCES errors, you probably installed Node from the system package manager rather than nvm. Remove the system version and reinstall with nvm.

Old Node version sticking around — which node shows you which binary is running. If it points to /usr/local/bin/node rather than ~/.nvm/..., you have a stale install ahead of nvm in your PATH.

What gets installed

When you install Node via nvm, you get:

• node — the runtime itself
• npm — the package manager (covered in npm and package.json)
• npx — a tool for running packages without installing them globally
• corepack — manages alternative package managers like pnpm and yarn

All four live under ~/.nvm/versions/node/<version>/bin/ and are automatically on your PATH when nvm is active.

Recap

You now know:

• nvm (or nvm-windows) is the cleanest way to install Node
• nvm install --lts gets you the current Long Term Support release
• node --version confirms what is active; nvm use <version> switches
• A .nvmrc file in a project pins the version for anyone who clones it
• node script.js runs a file; node alone opens the REPL
• process.argv exposes command-line arguments inside your script

Next steps

Now that Node runs, you need a way to organise code across multiple files and pull in libraries from the wider ecosystem. The next post covers exactly that.

Next: Node.js Modules — CommonJS vs ES Modules

Questions or feedback? Email codeloomdevv@gmail.com.