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Angular, the popular JavaScript framework, continues its journey of updation with the release of version 17, bringing some new improvements, and new features, as well as some breaking changes and deprecations.
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One of the standout features introduced in Angular v17 is deferrable views, which allow you to lazy load components, directives, and pipes within a section of their templates. This helps in more efficient rendering of large templates by deferring the loading of certain elements until they are needed. With the new @defer syntax, you can specify which parts of the template should be loaded lazily, improving the initial loading time and overall performance of Angular applications.
Angular v17 introduces a new block syntax for optimized, built-in control flow, resolving the issues faced with *ngIf, *ngSwitch, and *ngFor directives. The new syntax includes conditional statements, switch statements, and for loops, provide up to 90% faster performance for certain benchmarks. This enhancement streamlines the development process and enhances the readability of Angular templates.
With Angular v17, the server-side rendering (SSR) have been integrated more directly into the Angular CLI tooling. The new @angular/ssr package replaces @nguniversal/express-engine and provides equivalent functionality for adding SSR support to Angular applications. The Angular CLI now includes commands to add SSR capabilities to existing projects that simplifies the setup process and improving the development experience.
To improve the performance of Angular's SSR and SSG (static site generation), Angular v17 introduces a set of new lifecycle hooks. These hooks, including afterRender and afterNextRender, helps you to interact with elements safely and efficiently during the application lifecycle. By registering callbacks to be invoked after rendering, you can perform tasks such as instantiating third-party libraries or measuring element size without relying on DOM emulation.
In Angular v17, the Vite and esbuild-powered build experience becomes the default builder for all new applications. This enhancement brings significant performance improvements, with up to 87% faster build times for SSR and SSG applications. Additionally, the Angular team is working on schematics to help migrate existing applications to the new builder, further improving the development workflow.
Angular v17 introduces debugging APIs that enable you to inspect the injector tree and dependencies of Angular components directly within the browser DevTools. This enhancement provides greater visibility into the runtime behavior of Angular applications, simplifying the debugging process and improving the overall developer experience.
The View Transitions API introduced in Angular v17 helps in smooth transitions when changing the DOM, particularly when navigating between routes. With the new withViewTransitions feature in the Angular router, you can leverage the browser's native capabilities to create animated transitions between routes, enhancing the user experience of Angular applications.
While the update to Angular v17 brings significant improvements, you also need to know about certain breaking changes that might impact existing applications:
===) instead of the loose equality operator (==). This change may require you to adjust NgSwitch expressions or individual condition values to adapt with the stricter equality check.loadComponent no longer automatically inherit their data from their parent by default. In Angular v17, the default paramsInheritanceStrategy is emptyOnly. If you want to inherit parent data in child routes then you must update the strategy to always.setupTestingRouter and malformedUriErrorHandler from the RouterModule.forRoot options. You should use alternative methods, such as RouterModule.forRoot or UrlSerializer.parse, to handle routing and URL parsing errors effectively.zone-testing-bundle and zone-testing-node-bundle, are removed in Angular v17. This change affects imports from dist/, requiring to update import paths accordingly.OnPush change detection strategy, Angular v17 executes ngDoCheck during change detection if the component is dirty. You need to update tests or logic within ngDoCheck for dynamically instantiated components accordingly.provideRouter and RouterModule.forRoot. You should configure properties such as setupTestingRouter, paramsInheritanceStrategy, and others in provideRouter or RouterModule.forRoot as they are no longer part of the Router's public API.Angular v17 also marks certain features for deprecation, which indicates it will not be usable in future.
NoopAnimationDriver instead of AnimationDriver.NOOP to maintain compatibility with future versions of Angular. This change ensures consistency to Angular's deprecation policy.Before updating to Angular v17 you need to check:
Follow these steps to update your application:
ng update @angular/core@17 @angular/cli@17Once you have updated your application to v17, review your application and its interactions to ensure everything is working correctly. Make sure to test all functionalities and components to confirm that there are no regressions or unexpected behavior.
As Angular continues to evolve, updating applications to the latest version ensures access to new features, enhanced performance, and improved security. However, it's important to be aware of breaking changes and deprecations to avoid any potential issues during the update process.