What Is New in Angular 17.0
Angular 17.0 is a significant release that introduces a new declarative control flow, deferred views for lazy loading, and a fresh application template. It's a major step forward for developer experience and application performance.
| Category | Key Changes |
|---|---|
| New Features | Declarative control flow, Deferred views, New looping syntax |
| Improvements | SSR and Hydration enhancements, ESBuild dev server, Style and form updates |
| Developer Experience | New app template, Improved docs, Angular.dev preview |
How does the new declarative control flow work?
The new control flow is a built-in, HTML-based syntax that replaces *ngIf, *ngFor, and *ngSwitch. It's more type-safe, provides better ergonomics, and significantly improves performance by being a compile-time feature.
In practice, you now use @if, @for, and @switch blocks directly in your templates. This eliminates the need for the asterisk syntax and the underlying NgIf directive, making your templates more intuitive.
Example: Conditional Rendering
<div>
@if (user.isLoggedIn) {
<p>Welcome back!</p>
} @else {
<a routerLink="/login">Sign in</a>
}
</div>What are deferred views for lazy loading?
Deferred views allow you to declaratively lazy load a portion of a template and its dependencies. This is a game-changer for optimizing initial bundle size and load time without the complexity of manually setting up lazy-loaded routes.
You use the @defer block to wrap content that should be loaded later. You can specify triggers for when the loading should happen, like on viewport interaction, after a timer, or when the browser is idle.
Example: Defer on Viewport
@defer (on viewport) {
<app-heavy-comments-component />
} @placeholder {
<!-- Shown before loading -->
<p>Comments loading soon...</p>
} @loading {
<!-- Shown during loading -->
<spinner />
}What's new with server-side rendering and hydration?
Angular's SSR and hydration have graduated from developer preview to a stable, production-ready feature. The process is now more robust and provides a much smoother upgrade path for existing apps.
A key improvement is the ability to skip hydration for specific components or elements using the ngSkipHydration attribute. This is crucial for integrating third-party libraries or components that manipulate the DOM in ways incompatible with the hydration process.
<app-third-party-widget ngSkipHydration></app-third-party-widget>What tooling and build process improvements are there?
The Angular CLI now uses Vite with ESBuild as the development server for all new projects. This replaces Webpack dev server by default, resulting in significantly faster startup and update times during development.
For existing projects, you can migrate by updating your angular.json configuration. The change is mostly under the hood, so your development workflow remains familiar but much faster.
How has the developer experience been enhanced?
The starting experience for new developers is completely revamped. Running ng new presents an interactive prompt to help you set up SSR, SSG, and routing, making it easier to build optimized applications from day one.
The documentation is also moving to a new domain, angular.dev, which features improved guides, interactive tutorials, and a modernized look. The classic control flow directives are not deprecated yet, giving teams ample time to migrate at their own pace.
FAQ
Is the old *ngIf/*ngFor syntax being removed?
No, the structural directives like *ngIf and *ngFor are not deprecated in v17. The new @if and @for control flow is an additive feature. You can migrate your templates when you're ready.
Do I have to use Vite and ESBuild now?
New projects created with Angular CLI 17.0+ will use Vite by default. Existing projects continue to use Webpack unless you manually update your build configuration in angular.json.
Can I use deferred views for lazy loading components?
Absolutely. Deferred views (@defer) are the new primary way to lazy load individual components within a route. They are more flexible and declarative than the previous method of using dynamic imports with ngComponentOutlet.
What's the benefit of the new built-in for loop?
The new @for loop has significantly better performance than *ngFor. It also includes built-in tracking, eliminating the need for the trackBy function in most cases, which reduces boilerplate and potential bugs.
Is the hydration process automatic now?
Yes, for apps using SSR, the hydration process is now enabled and stable by default. You can control it more granularly with the ngSkipHydration attribute on specific elements that should be skipped.