npm scripts

Package scripts are the contract for how a repo is developed, tested, built, and run — they encode repeatable commands and hide toolchain details.

					{
  "scripts": {
    "dev": "node --watch src/server.js",
    "build": "tsc -p tsconfig.build.json",
    "start": "node dist/server.js",
    "test": "vitest run",
    "lint": "eslint .",
    "prestart": "npm run build"
  }
}
				

`npm run` adds `node_modules/.bin` to PATH — local CLIs without global installs. Lifecycle hooks (`pre*`, `post*`) chain steps but can surprise CI if overused.

Cross-platform scripts: prefer small Node wrappers or tools like `cross-env` instead of shell-specific syntax unless documented for Unix-only dev.

On interviews: describe how you structure scripts for CI vs local dev, `prepare` for git hooks, and why `npm test` should be the single entry for verification.

Common pitfalls: business logic buried in bash one-liners; scripts that mutate global state; missing `CI=true` behavior branches.

The trade-off is balancing simplicity, performance, safety, and operability — name which axis you optimized and what cost you accepted.

Checklist:

• One obvious command per task (`test`, `build`, `dev`).
• Pin toolchain via devDependencies.
• Keep scripts idempotent for CI.
• Document env vars scripts expect.