In short
Your first real Node project doesn't need a browser at all. A command-line tool teaches arguments, files, exit codes and packaging: the same basics every backend service relies on.
A command-line tool (e.g. a task manager or file renamer) — practice for `process.argv`, the `fs` module, and packaging a script as a runnable CLI.
Think of it like this
The office tea vending machine
Press a button, maybe pick 'extra sugar', and you get the same tea every time. If it's out of milk, it flashes an error instead of pouring hot water. A good CLI tool is that machine: clear options in, predictable output out, honest errors.
Watch it happen
What happens when you run greet
1/5Read flags like --name Asha --shout from process.argv using util.parseArgs.
The big ideas
What you need to know
A real --help
Show usage and every option with --help. It's the first thing people try.
stdout for results, stderr for errors
Keeping them apart lets users redirect results to a file without error messages mixed in.
Meaningful exit codes
0 means success, anything else means failure. Shell scripts and CI pipelines depend on it.
Installable with bin
A "bin" entry in package.json plus npm link turns your script into a command you can run anywhere.
See it in code
Walk through the code
1#!/usr/bin/env node2import { parseArgs } from "node:util";3 4const { values } = parseArgs({5 options: {6 name: { type: "string", short: "n" },7 shout: { type: "boolean", default: false },8 help: { type: "boolean", short: "h" },9 },10});11if (values.help || !values.name) {12 console.error("Usage: greet --name <name> [--shout]");13 process.exit(values.help ? 0 : 1);14}15const msg = `Namaste, ${values.name}!`;16console.log(values.shout ? msg.toUpperCase() : msg);1/4The shebang tells the OS to run this file with node when you type greet.
Save as bin/greet.js in a package with "type": "module" and "bin": { "greet": "bin/greet.js" }. Run chmod +x on it, then npm link. parseArgs throws on unknown flags by default.
Save yourself the pain
Common mistakes
Oops
Printing errors with console.log, so they mix into the real output.
Do this instead
Send errors to stderr with console.error. Then greet -n A > out.txt keeps only real results in the file.
Oops
Always exiting with code 0, even when something failed.
Do this instead
Set process.exitCode = 1, or call process.exit(1), on errors so shell scripts and CI can detect them.
Your mission
First milestone: ship greet v1
Quick check
Your CLI can't find the input file the user gave it. What should it do?
Go deeper
- 1Parse command-line arguments manually or with a library like `commander`.
- 2Add colored terminal output for better UX, e.g. with `chalk`.
- 3Package it with a `bin` field in `package.json` so it can be installed globally.
More projects at this stop
File Organizer Script
Simple HTTP Server (No Framework)
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