npm-package-check

NPM Package Check

// Description: Best practices for checking and installing NPM packages before use // Recommended Globs: **/*.{js,jsx,ts,tsx}, **/package.json

Overview

Ensure all required NPM packages are properly installed before use to prevent runtime errors.

Package Check Process

1. Before requiring any npm package, check package.json dependencies
2. If package exists in dependencies:
   • Output: "✓ {package_name} is already installed"
3. If package NOT found:
   • Output terminal command: npm install {package_name}

Example Implementation

const fs = require('fs');
const path = require('path');

function checkPackage(packageName) {
  try {
    const packageJson = JSON.parse(
      fs.readFileSync(path.join(process.cwd(), 'package.json'), 'utf8')
    );

    const deps = {
      ...packageJson.dependencies,
      ...packageJson.devDependencies
    };

    if (deps[packageName]) {
      console.log(`✓ ${packageName} is already installed`);
      return true;
    } else {
      console.log(`Installing ${packageName}...`);
      console.log(`Run: npm install ${packageName}`);
      return false;
    }
  } catch (error) {
    console.error('Error reading package.json:', error);
    return false;
  }
}

Usage Example

// Before importing a package
if (checkPackage('express')) {
  const express = require('express');
  // Use express...
} else {
  console.error('Please install express first');
  process.exit(1);
}

Best Practices

• Always check packages before requiring them
• Handle missing package.json gracefully
• Consider both dependencies and devDependencies
• Provide clear installation instructions
• Exit gracefully if required packages are missing

Common Patterns

• Pre-startup dependency check
• Dynamic package loading
• Development tooling setup
• Build process validation