Exploring package.json — Querying Your Node.js Project Metadata

2026-02-20 · By Udi Talias

Every Node.js project starts with package.json. It's the manifest for your application — dependencies, scripts, metadata, build configuration, and more. In small projects, it's easy to scan. In large monorepos or mature applications, it becomes a 200-line file where finding what you need takes real effort.

Here's how to use JSON querying to extract exactly what you need from package.json files.

Inspecting Dependencies

A typical production package.json has dozens of dependencies. To see just your production deps:

{
  "name": "my-web-app",
  "version": "2.4.1",
  "dependencies": {
    "express": "^4.18.2",
    "pg": "^8.11.3",
    "redis": "^4.6.7",
    "zod": "^3.22.4",
    "pino": "^8.16.2",
    "helmet": "^7.1.0",
    "cors": "^2.8.5"
  },
  "devDependencies": {
    "typescript": "^5.3.3",
    "vitest": "^1.2.0",
    "eslint": "^8.56.0",
    "@types/express": "^4.17.21",
    "@types/cors": "^2.8.17",
    "prettier": "^3.2.4",
    "tsx": "^4.7.0"
  }
}

Query dependencies to see just the runtime deps. Query devDependencies to see tooling. This is especially useful when reviewing a new project — you can quickly understand the tech stack without scrolling through the entire file.

Listing All Scripts

In mature projects, the scripts section grows large:

{
  "scripts": {
    "dev": "tsx watch src/server.ts",
    "build": "tsc && node scripts/build.mjs",
    "start": "node dist/server.js",
    "test": "vitest run",
    "test:watch": "vitest",
    "test:coverage": "vitest run --coverage",
    "lint": "eslint src/",
    "lint:fix": "eslint src/ --fix",
    "format": "prettier --write src/",
    "db:migrate": "node scripts/migrate.mjs",
    "db:seed": "node scripts/seed.mjs",
    "db:reset": "node scripts/migrate.mjs --fresh && node scripts/seed.mjs",
    "docker:up": "docker compose up -d",
    "docker:down": "docker compose down",
    "deploy:staging": "node scripts/deploy.mjs --env staging",
    "deploy:production": "node scripts/deploy.mjs --env production"
  }
}

Query scripts and you get a clean view of every available command. No need to open the file and scroll past dependencies, engine requirements, and other sections.

Checking Specific Configuration

Many tools store their config inside package.json rather than in separate files. ESLint, Prettier, Jest, Babel — they all support package.json configuration:

{
  "name": "my-app",
  "prettier": {
    "semi": false,
    "singleQuote": true,
    "tabWidth": 2,
    "trailingComma": "es5",
    "printWidth": 100
  },
  "eslintConfig": {
    "extends": ["eslint:recommended", "plugin:@typescript-eslint/recommended"],
    "rules": {
      "no-unused-vars": "off",
      "@typescript-eslint/no-unused-vars": "error",
      "no-console": "warn"
    }
  }
}

Query prettier or eslintConfig.rules to inspect specific tool configurations without noise from the rest of the file.

Comparing Versions Across Projects

When you're maintaining multiple services, you need to check if dependencies are aligned. Copy dependencies from one package.json and dependencies from another, then use the Compare tool to see which packages differ and which versions are out of sync.

This is especially valuable for:

• Monorepo packages that should share dependency versions
• Microservices that need compatible library versions
• Upgrading a library across multiple projects

Inspecting Lock Files

package-lock.json files are notoriously large — thousands of lines. You almost never read them directly, but sometimes you need to check the exact resolved version of a transitive dependency.

Use recursive descent: ..node_modules..lodash finds every resolved instance of lodash in the dependency tree. Or query packages["node_modules/lodash"].version for the top-level resolved version.

Workspace Queries in Monorepos

In npm/yarn/pnpm workspaces, the root package.json defines the workspace structure:

{
  "name": "monorepo",
  "private": true,
  "workspaces": [
    "packages/core",
    "packages/api",
    "packages/web",
    "packages/shared"
  ],
  "scripts": {
    "build": "npm run build --workspaces",
    "test": "npm run test --workspaces"
  }
}

Query workspaces to see all packages at a glance. In tools like Turborepo or Nx, the workspace config gets more complex — json.express's Tree view helps navigate the dependency graph configuration without getting lost.

Quick Reference

Here are the most useful queries for package.json exploration:

• name — project name
• version — current version
• scripts — all available npm scripts
• dependencies — production dependencies
• devDependencies — development dependencies
• engines — required Node.js/npm versions
• peerDependencies — peer dependency requirements
• exports — package entry points (ESM/CJS)

Each of these pulls out exactly the section you need from even the largest package.json files. It's faster than opening the file and scrolling, and cleaner than piping cat package.json | jq '.scripts' in the terminal.