Upgrading your Angular application to version 18, you can follow these several steps.

Backup Your Project: Before starting the upgrade process, make sure to back up your project to prevent any data loss.

Check Current Version: Verify your current Angular version by running:

ng version

Globally Update Angular CLI: Upgrade the Angular CLI globally to the latest version.

npm install -g @angular/cli@latest

Update Local Angular CLI and Angular Core: Navigate to your project directory and update the local Angular CLI and core packages.

ng update @angular/cli @angular/core

Review Breaking Changes: Review the Angular 18 release notes for any breaking changes. Make sure to address them before proceeding.

Run Update Schematics: Angular provides update schematics to automatically apply necessary code changes.

ng update @angular/core@18 @angular/cli@18

Update Third-Party Dependencies: Ensure all third-party dependencies are compatible with Angular 18. Check the documentation of each dependency and update them accordingly.

npm outdated
npm install <package-name>@latest

Update RxJS: If your project uses RxJS, update it to the latest version compatible with Angular 18.

ng update rxjs

Run Unit Tests: Execute your unit tests to ensure that your application is functioning correctly.

ng test 

Run End-to-End Tests: Perform end-to-end tests to validate the overall behavior of your application.

ng e2e 

Manual Testing: Conduct thorough manual testing to catch any issues that automated tests might miss.

Optimize Code: Utilize Angular 18’s new features and optimizations. For instance, if Angular 18 introduces new lazy loading techniques or performance improvements, integrate them into your application.

Refactor Deprecated APIs: Replace any deprecated APIs with their recommended alternatives. Refer to the Angular documentation for guidance on deprecated features and their replacements.

Update Project Documentation: Reflect any changes made during the upgrade process in your project’s documentation.

Check and Update Configurations: Review and update your project’s configuration files, such as angular.json, tsconfig.json, and other environment-specific settings.

Build the Application: Generate a production build of your application.

ng build --prod

Deploy the Application: Deploy the updated application to your hosting environment.

Upgrading to Angular 18 involves several steps, from updating dependencies and handling breaking changes to testing and optimizing your code. By following this step-by-step guide, you can ensure a smooth transition to Angular 18. Always refer to the official Angular update guide for the most accurate and detailed instructions tailored to your specific Angular version upgrade path.

For detailed information on breaking changes and specific migration instructions, refer to:

• Angular 18 Release Notes
• Angular Update Guide
• Angular CLI Documentation