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How To Exclude An External Library From Ngcc

7 min read 11-15- 2024
How To Exclude An External Library From Ngcc

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When working with Angular projects, particularly those involving Angular Ivy, the Angular compatibility compiler (ngcc) becomes a crucial player in ensuring that external libraries work seamlessly with the framework. However, there may be instances where you might want to exclude certain external libraries from ngcc for various reasons. This article will guide you through the process of excluding an external library from ngcc, explaining its importance, the steps involved, and best practices to consider.

Understanding ngcc and Its Purpose

What is ngcc?

The Angular compatibility compiler, or ngcc, is a tool that processes node modules that are in the View Engine format (the earlier rendering engine of Angular) and converts them into Ivy-compatible format. This conversion is necessary for Angular applications utilizing Ivy to take full advantage of the new rendering engine's performance enhancements and features.

Why Exclude a Library?

Excluding a library from ngcc may be necessary in various scenarios:

  1. Performance Optimization: If a library is already Ivy-compatible or does not need conversion, excluding it can reduce build time.
  2. Compatibility Issues: Some libraries might have known issues with ngcc or Ivy. Excluding them can prevent compilation errors.
  3. Customization: In certain cases, you may want to include a library in a different manner that does not require ngcc processing.

Steps to Exclude an External Library from ngcc

Now that we have established why one might want to exclude a library, let's go through the steps to effectively achieve this.

Step 1: Identify the Library

Before excluding a library from ngcc, you need to determine which library you want to exclude. Make sure you have the library's name handy as you will need to reference it in the configuration.

Step 2: Update the ngcc.config.js File

The key to excluding a library from ngcc is to create or update a configuration file named ngcc.config.js. This file allows you to customize the behavior of ngcc.

Here is how you can structure your ngcc.config.js file:

module.exports = {
  packages: {
    'your-external-library': {
      entryPoints: {
        '.': {
          // Ensure this library is excluded
          'typings': false,
          'ngcc': false,
        }
      }
    }
  }
};

Step 3: Modify the tsconfig.json File (If Necessary)

In some cases, you might also need to update your tsconfig.json file to inform TypeScript not to check for certain modules or to reflect the changes made in the ngcc.config.js. Here’s an example modification:

{
  "compilerOptions": {
    "skipLibCheck": true,
    "paths": {
      "your-external-library": [
        "node_modules/your-external-library"
      ]
    }
  }
}

Step 4: Run ngcc

After configuring the ngcc settings, the final step is to run ngcc again to ensure the changes take effect. You can do this by running:

ngcc

This command will process the libraries, and the specified library will be excluded from the ngcc processing.

Important Notes

  • Always Backup Your Configurations: Before making any changes, ensure you have a backup of your configuration files. This allows you to revert changes if necessary.
  • Test After Exclusion: After excluding a library from ngcc, make sure to thoroughly test your application. Verify that everything works as expected without any errors.
  • Monitor for Updates: Libraries can be updated frequently. Keep an eye on the libraries you exclude from ngcc and check if newer versions might be Ivy-compatible.

Best Practices

Keep Dependencies Updated

Always aim to use the latest versions of your dependencies. Many libraries have started supporting Ivy, and using an updated version could eliminate the need for exclusion.

Monitor Performance

After excluding libraries, regularly monitor your application's performance and behavior. This can help identify if the exclusion negatively impacts performance or causes issues in other areas.

Consult Documentation

Each library may have specific notes regarding ngcc compatibility. Always refer to the documentation of the external library for any recommended practices when using it with Angular.

Use Angular CLI

Consider using Angular CLI for managing your project, as it integrates well with ngcc and may offer tools to manage external libraries more effectively.

Conclusion

Excluding an external library from ngcc can enhance your development experience and ensure that your Angular project runs smoothly. By understanding how ngcc works, identifying the libraries you want to exclude, and carefully configuring the settings, you can achieve optimal performance for your application. Remember to stay updated with both Angular and the libraries you use to leverage the best of both worlds in your development projects. Happy coding! 😊

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