How to handle legacy code after upgrading to Angular v15?

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Refactor the codebase: The first step in dealing with legacy code is to refactor it into a more organized and robust structure. Identify the common coding patterns and refactor them using Angular best practices. This not only improves the code quality but also makes it easier to maintain and upgrade in the future.

Migrate to Angular CLI: Angular CLI (Command Line Interface) provides a standardized build pipeline and project structure. Migrating your legacy codebase to Angular CLI can simplify development and improve consistency.

Upgrade dependencies: Upgrading dependencies such as Angular Material, RxJS, and TypeScript can improve performance and add new features. Make sure to verify that your codebase is compatible with the latest versions of these dependencies.

Write unit tests: Unit testing allows you to catch errors early in the development cycle and ensure that the codebase is stable when upgrading. Write unit tests for the legacy codebase to ensure that it behaves as expected after the upgrade.

Use Angular Schematics: Angular Schematics provide a way to automate common tasks such as component and module creation, making it easier to add new features to the codebase.

Embrace Angular Ivy: Ivy is the new rendering engine included in Angular v9 and higher. It brings a number of benefits, including improved performance and smaller bundle sizes. Migrating to Ivy may require some changes to your legacy codebase, but it's worth the effort in the long run.

Keep up with best practices: Stay informed about the latest best practices in Angular development and apply them to your legacy codebase. This ensures that your code is well-structured, efficient, and consistent with the latest Angular standards.