Node.js

Run Commands

Execute Node.js scripts and applications from the command line. Learn to run files, evaluate expressions, use experimental features, and configure the runtime environment.

8 commands

Pro Tips

Use 'node --watch app.js' (Node 18+) for automatic restarts on file changes — no nodemon needed.

Use 'node -e "console.log(process.versions)"' to quickly check installed versions of V8, OpenSSL, etc.

Enable ESM in CommonJS projects with 'node --experimental-vm-modules' or rename files to .mjs.

Common Mistakes

--experimental flags can change or be removed between Node.js versions. Don't rely on them in production.

node --watch restarts the entire process on changes. In-flight requests are dropped — use proper graceful shutdown.

Commands

Run script

$ node app.js

Execute JavaScript file.

Evaluate code

$ node -e "console.log('Hello')"

Evaluate JavaScript code directly.

Print expression

$ node -p "1 + 2"

Evaluate and print result.

Watch mode

$ node --watch app.js

Auto-restart on file changes (Node.js 22+).

Watch specific paths

$ node --watch-path=./src app.js

Watch specific directories for changes.

Preserve output on restart

$ node --watch --watch-preserve-output app.js

Keep console output between restarts.

Run package script

$ node --run dev

Run package.json script (faster than npm run).

Load env file

$ node --env-file=.env app.js

Load environment variables from file.