Angular 5 / AoT / Webpack / Code splitting issues

When working with Angular 5, Ahead-of-Time (AoT) compilation, Webpack, and code splitting, there can be various issues that arise due to the complexity of these technologies working together. Below are some common issues and their potential solutions:

1. Lazy Loading and Code Splitting Not Working:

   • Ensure that you have set up lazy loading correctly in your routing configuration. Lazy loading allows you to split your code into smaller bundles that are loaded on-demand.
   • Verify that the paths to the lazy-loaded modules are correct in your routing configuration.
   • Check for any errors in the browser console that might be preventing lazy loading.

2. Duplicate Libraries in Multiple Bundles:

   • When using code splitting, some shared libraries may end up duplicated in multiple bundles, leading to larger bundle sizes.
   • Consider using the CommonsChunkPlugin (available in Webpack 3) or SplitChunksPlugin (available in Webpack 4) to extract common code into separate chunks and prevent duplication.

3. Vendor Bundle Size Too Large:

   • Check the size of your vendor bundle, which includes third-party libraries.
   • Consider using the DllPlugin (Webpack 3) or DllReferencePlugin (Webpack 4) to create a separate vendor bundle that doesn't need to be recompiled with every build. This can speed up build times and reduce the size of the main bundle.

4. Webpack Build Configuration Errors:

   • Make sure your Webpack configuration is set up correctly for AoT compilation and code splitting.
   • Double-check the configuration for plugins, loaders, and optimization settings.

5. Module Not Found Errors:

   • If you encounter "Module not found" errors during the build, check that the import paths in your code are correct and match the file structure.

6. Circular Dependency Issues:

   • Avoid circular dependencies between modules, as they can lead to issues during AoT compilation and code splitting.

7. Polyfills and Bundles:

   • Ensure that you have included the necessary polyfills for the browsers you want to support. Different browsers may require different polyfills, and omitting them can lead to errors or unexpected behavior.
   • Consider creating separate bundles for modern browsers and legacy browsers to reduce the size of the polyfills.

8. Webpack Upgrade:

   • If you encounter issues related to Webpack, consider upgrading to a newer version of Webpack, as newer versions often come with performance improvements and bug fixes.

9. Angular CLI and Build Configurations:

   • If you are using Angular CLI, check the build configurations in angular.json or angular-cli.json to ensure that AoT compilation and code splitting are enabled correctly.

Remember to check the browser console for any error messages or warnings that can provide insights into the specific issues you are facing. Additionally, using development tools like Webpack Bundle Analyzer can help analyze your bundles and identify potential optimizations.