Angular 17: A Comprehensive Look at What’s New

Angular 17, released on November 6, 2023, marked a significant step forward for this popular JavaScript framework. It introduced a range of innovative features designed to enhance developer experience, improve application performance, and streamline the development process. This article delves into these new features, explaining them in a beginner-friendly manner and providing practical examples for better understanding.

Angular 17: A Comprehensive Look at What’s New

1. Typescript 5.2

Angular 17 introduces better TypeScript support, specifically version 5.2. Here’s a concise summary in under 10 lines:

• Angular 17 embraces TypeScript 5.2: This integration brings improved type-checking and modern language features to your Angular projects.
• Enhanced Type Safety: With TypeScript 5.2, you can benefit from stricter type checking, leading to fewer runtime errors and a more robust codebase.
• Modern Language Features: Leverage features like template literal types, improved enums, and refined control flow analysis for a more efficient and expressive development experience.

In essence, Angular 17 and TypeScript 5.2 go hand-in-hand to deliver a smoother and more robust development workflow.

2. New Declarative Control Flow

Angular 17 introduces a new way to manage template structure using keywords:

• Replaces *ngIf, *ngFor, and *ngSwitch directives.
• Uses cleaner syntax like @if, @for, and @switch.
• Improves code readability and maintainability.
• Offers a more intuitive way to control template flow.

HTML

@for (product of products(); track product.id) {
    <div class="card">
        <h2 class="card-title">{{product.productName}}</h2>
        […]
    </div>
    }
@empty {
    <p class="text-lg">No Products found!</p>
}

• @for replaces *ngFor: It iterates over a function call products() that presumably returns an array of products.
• track by product.id: Improves performance by tracking products using their unique id.
• Content inside @for: Renders for each product, likely displaying details like name (product.productName) within a card structure.
• Empty State: The @empty block handles the scenario where products() returns no items.
• No Products Found Message: If empty, displays a message indicating no products were found.

3. Deferrable Loading

Angular 17’s Deferrable Loading (using @defer) lets you delay loading parts of your template until needed. Here’s the gist in under 10 lines:

• @defer Block: Wraps a section of your template that can be deferred.
• Lazy Loading: Delays loading the components, directives, and pipes within that section.
• Improved Initial Load: Reduces initial bundle size for faster page load.
• Triggers: Control when to load the deferred content – based on time, user interaction, or other conditions.
• Placeholders: Optionally define content to display while the deferred section loads.

This helps optimize performance by prioritizing essential content initially and loading less critical sections later.

HTML

@defer(on timer(1000ms)){
<router-outlet></router-outlet>
}

@defer(on viewport){
<router-outlet></router-outlet>
}@placeholder{
<div>data is available soon....</div>
}


@defer(on interaction(headertext)){
<router-outlet></router-outlet>
}@placeholder{
<div>data is available soon....</div>
}


@defer(on hover){
<router-outlet></router-outlet>
}@placeholder{
<div>data is available soon....</div>
}

@defer(on immediate){
<router-outlet></router-outlet>
}@placeholder{
<div>data is available soon....</div>
}

<button (click)="showcontent()">Click</button>
@defer(when isloadcontent){
<router-outlet></router-outlet>
}@placeholder{
<div>data is available soon....</div>
}

<button (click)="showcontent()">Click</button>
@defer{
<router-outlet></router-outlet>
}@placeholder( minimum 2s){
<div>data is available soon....</div>
} @loading(after 100ms; minimum 1s){
<div>Loading....</div>
} @error{
<div>Failed to load content</div>
}


<button (click)="showcontent()">Click</button>
@defer(when isloadcontent;on timer(1000ms)){
<router-outlet></router-outlet>
}@placeholder(){
<div>data is available soon....</div>
} @loading(after 100ms; minimum 1s){
<div>Loading....</div>
} @error{
<div>Failed to load content</div>
}

<button (click)="showcontent()">Click</button>
@defer(when isloadcontent;prefetch on idle){
<router-outlet></router-outlet>
}@placeholder(){
<div>data is available soon....</div>
} @loading(after 100ms; minimum 1s){
<div>Loading....</div>
} @error{
<div>Failed to load content</div>
}

Key Points:

• Defer Blocks: Enclose content to be loaded only when triggered, using @defer.
• Triggers: Specify when to load using options like on timer, on viewport, on interaction, on hover, on immediate, and when (evaluating a condition).
• Placeholders: Show temporary content while loading or prefetching using @placeholder.
• Loading Indicators: Display loading states with @loading.
• Error Handling: Catch loading errors with @error.

Example Highlights:

• Loading after a timer: @defer(on timer(1000ms))
• Loading when entering viewport: @defer(on viewport)
• Loading on interaction with an element: @defer(on interaction(headertext))
• Loading on hover: @defer(on hover)
• Triggering loading with a button click: @defer(when isloadcontent)
• Combining triggers and conditions: @defer(when isloadcontent; on timer(1000ms))
• Prefetching content on idle: @defer(when isloadcontent; prefetch on idle)

4. Support for View Transition API

• Smoother Animations: Angular 17 lays the groundwork for improved animations and transitions between views.
• Experimental Feature: This functionality is still under development but offers a glimpse into future possibilities.
• Leverages Web Animations API: It utilizes the browser’s built-in animation capabilities for efficient rendering.
• Limited Browser Support: Currently works primarily in Chrome/Chromium browsers.
• Enhanced User Experience: Polished UI transitions can make your web app feel more engaging and user-friendly.

To use view transitions API with the router, all you need to do is add “withViewTransitions” to the “provideRouter” in your ApplicationConfig:

JavaScript

export const appConfig: ApplicationConfig = {
  providers: [
    provideAnimations(),
provideRouter(
        routes, 
        withViewTransitions(),   // 
        withComponentInputBinding()
   )]
};

5. Improved Server-Side Rendering

1. New @angular/ssr Package: This simplifies setup and integration of SSR into your Angular project.
2. Streamlined Rendering: The rendering process is optimized for faster server responses, potentially improving initial load times.
3. SEO Benefits: By efficiently rendering content on the server, Angular 17 enhances SEO as search engines can more effectively crawl and index your application’s content.

Additional Information: This feature was the most requested update from the Angular developer community. Due to that, improving server-side rendering was the priority for the Angular team.

6. Router Refactoring

• Inline Route Configuration: You can now define routes directly in templates using the routerLink directive.
• Simpler Syntax: The syntax for inline route configuration mirrors the one used for traditional route configuration in RouterModule.
• Reduced Code: This eliminates the need to switch between component files and routing modules for basic route definitions.
• Improved Maintainability: Centralized routing configurations might still be preferred for complex applications, but this new feature enhances code organization for simpler scenarios.

7. Upgrade to Node js 18.13.0

Angular 17 requires upgrading to Node.js version 18.13.0 or higher. Here’s why:

• Breaking Change: Node.js versions below 18.13.0 are incompatible with Angular 17.
• Modern Features: Node.js 18.13.0 offers new features and improvements Angular 17 relies on.
• Long-Term Support (LTS): Version 18.13.0 is an LTS release, guaranteeing support for at least two years, ensuring stability for your Angular application.
• Upgrade Necessity: Upgrading Node.js is essential to leverage Angular 17’s features and maintain a secure development environment.

How to Upgrade Angular v16 to Angular v17

Upgrading from Angular 16 to 17 can be done with these steps:

1. Update CLI Globally: Use npm install -g @angular/cli@17 to update the Angular CLI.
2. Project Directory: Navigate to your Angular project’s directory.
3. Run Update Command: Execute ng update @angular/core @angular/cli to update core packages.
4. Further Updates: Depending on your project setup, you might need to update other dependencies. Refer to the official guide for details.

Conclusion

Angular 17 marks a significant leap forward for crafting high-performance and user-friendly web applications. By embracing features like improved TypeScript support, declarative control flow (experimental), streamlined server-side rendering (SSR), and Node.js 18.13.0 compatibility, Angular empowers developers to build robust and performant web experiences. Whether you’re a seasoned Angular developer or just starting your framework journey, Angular 17 offers exciting possibilities for creating next-generation web apps.