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npm Scripts

Project commands defined in package.json.

Also known as: package.json scripts, npm run, npm run scripts, scripts section

The "scripts" section of package.json names the commands for working on a project. Instead of remembering long invocations, everyone runs the same short ones.

{
  "scripts": {
    "dev": "vite",
    "build": "tsc && vite build",
    "test": "vitest run",
    "lint": "eslint .",
    "format": "prettier --write ."
  }
}

npm run dev
npm run build
npm test            # `test`, `start` and a few others can skip "run"

(pnpm run dev and yarn dev work the same way.)

Why it’s useful

• One way to run things. A new teammate learns the project by reading the scripts section, and CI calls the same commands.
• Local tools just work. npm adds node_modules/.bin to the PATH while running a script, so vite or eslint is found without installing it globally, and the version matches the project.
• Composable: "check": "npm run lint && npm test". && stops at the first failure.

Tips

• Use conventional names: dev, build, test, lint. Anyone can then guess them.
• Pass extra arguments after --: npm test -- --watch.
• pre and post prefixes (prebuild, postbuild) run automatically around a script, though many teams now prefer explicit commands. Check what your version of npm does.
• Keep scripts short. If one gets long or needs logic, move it into a file (node scripts/seed.js) or a task runner.
• Shell syntax in scripts can differ between operating systems (Windows vs Linux/macOS), so avoid shell-specific features if your team uses both.
• Be careful with install scripts in dependencies. They run code on your machine.

npm run with no name lists the scripts that are available.