JavaScript — Installation & Setup

JavaScript is unusual among languages covered on this platform: you can start writing and running it with zero install, because every browser already has a JavaScript engine built in. Real development work, though, needs a bit more — Node.js for running scripts outside the browser and for the tooling (npm) the rest of the JavaScript ecosystem is built on.

Option 1: Browser Console (zero install, fastest way to start)

Every browser ships a JavaScript console for free.

1.Open any web page.

2.Press F12 (Windows/Linux) or Cmd+Option+I (Mac) to open DevTools.

3.Click the Console tab.

4.Type console.log("hello") and press Enter.

This is genuinely how most people write their first JavaScript, and it's still how experienced developers quickly test a snippet or inspect a live page's state. It's the right tool for the Overview and Fundamentals "Try it" exercises. Its limit: nothing you write here is saved, and it can't read/write files or talk to most external services the way a real script can.

Option 2: Node.js (for real scripts, npm, and tooling)

Node.js runs JavaScript outside the browser — on your machine, in a terminal, or on a server. It's required for anything beyond quick console experiments: running a .js file directly, installing packages with npm, and using any real-world JavaScript build tooling.

Recommended: install via nvm (Node Version Manager), not a direct installer — JavaScript projects frequently pin specific Node versions, and nvm lets you switch between them per-project instead of fighting a single system-wide install.

bash

# macOS / Linux
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.1/install.sh | bash
# restart your terminal, then:
nvm install --lts
nvm use --lts

# Windows: use nvm-windows instead (a separate project, different installer)
# https://github.com/coreybutler/nvm-windows

Verify it worked:

bash

node --version   # should print something like v22.x.x
npm --version    # npm ships bundled with Node

(needs verification — recheck against current source: exact current LTS version number changes regularly — nvm install --lts always grabs whatever is current)

Option 3: Code Editor with JS Tooling

VS Code (free, most widely used for JavaScript specifically) is the practical default. On install, add:

•The built-in JavaScript/TypeScript language support (already bundled — no extension needed for basic syntax highlighting and autocomplete).

•ESLint extension — catches real bugs before you run the code (an unused variable, a missing await, an unreachable case), not just style nits.

•Prettier extension (optional but common) — auto-formats code consistently, so code review isn't spent on spacing debates.

Running a Script Both Ways

Create a file called hello.js:

javascript

console.log("Hello from JavaScript!");

const sum = (a, b) => a + b;
console.log("2 + 3 =", sum(2, 3));

Run it with Node.js (from a terminal, in the same folder):

bash

node hello.js

Run the same logic in a browser — save this as hello.html in the same folder and open it in a browser:

html

<!DOCTYPE html>
<html>
<body>
  <script src="hello.js"></script>
</body>
</html>

Open DevTools' Console tab on that page — the same output appears there. This is the core thing to internalize early: the language is identical in both places; what differs is the environment around it — Node.js gives you access to the filesystem and OS, a browser gives you the DOM and window, and each has APIs the other doesn't.

Verify Everything Works

bash

node --version      # Node installed and on PATH
npm --version        # npm installed (bundled with Node)
node hello.js         # runs your script, prints to the terminal

If node hello.js prints the two lines above, you have a complete working JavaScript setup — browser console for quick experiments, Node.js + a real editor for everything else.