Checking for Unused Libraries with depcheck

Introduction

Keeping your project clean and efficient is crucial, especially when dealing with dependencies. Over time, unused libraries can accumulate, bloating your node_modules folder and potentially causing conflicts. In this post, I'll show you how I used depcheck to identify and remove unnecessary dependencies from a Node.js project.

Preface

• Tool Used: depcheck
• Purpose: Find unused npm packages and clean up your node_modules
• Prerequisite: Your project must contain a package.json file

Solution

1. Install depcheck Globally
   To begin, install depcheck globally on your system by running:

   npm install -g depcheck
   

2. Run depcheck
   Navigate to the folder where you want to check for unused dependencies. Make sure this folder contains your package.json file. Run the following command:

   depcheck
   

3. Review the Output
   If you’ve installed a package, say react-bootstrap, but haven’t imported anything from it, depcheck will list it under Unused dependencies. Example Output:

   Unused dependencies
   * react-bootstrap
   
   Missing dependencies
   * ...
   

4. Remove Unused Packages
   Once identified, you can remove any unwanted packages by running:

   npm uninstall <package_name>
   

   For example:

   npm uninstall react-bootstrap
   

Why

• Improved Performance: Smaller node_modules directory resulting in faster installations and deployments.
• Reduced Security Risks: Fewer dependencies reduce the attack surface for potential vulnerabilities.
• Cleaner Codebase: Less clutter means a more maintainable project.

Limitations

• depcheck may occasionally report false positives, particularly for packages used dynamically (e.g., via require() or with unconventional import structures).
• Dependencies listed as peerDependencies or devDependencies may require careful consideration before removal.

Conclusion

Using depcheck is a straightforward way to ensure your Node.js projects remain free from unnecessary dependencies. Regularly running this tool can help you maintain a cleaner and more efficient codebase.

Further Reading

For more details, refer to the official depcheck documentation.