The New Angular Maximizing Performance and Productivity Christian Liebel @christianliebel Consultant

Hello, it’s me. The New Angular Maximizing Performance and Productivity Christian Liebel X: @christianliebel Email: christian.liebel @thinktecture.com Angular & PWA Slides: thinktecture.com /christian-liebel

The New Angular Maximizing Performance and Productivity “Angular Renaissance”

Angular 16+ – Signals, Signal-based inputs (…and a Zone.js-less future) – Standalone Components/APIs – Built-in Control Flow/Deferrable Views – Server-Side Rendering/Hydration (…and new build tools: esbuild & Vite) Goals: Streamline & modernize APIs & improve performance The New Angular Maximizing Performance and Productivity “Angular Renaissance”

Angular 16+ But: The shape of Angular apps changes significantly. You can tell the difference between an Angular 2 and an Angular 18 app. No worries: All new features are backwards compatible & interoperable. Not another AngularJS scenario. Still: You should migrate your applications as soon as possible. In this session, we talk about why, when and how you should migrate. The New Angular Maximizing Performance and Productivity “Angular Renaissance”

Signals Standalone Components and APIs Built-in Control Flow and Deferrable Views Server-Side Rendering, esbuild and Vite The New Angular Maximizing Performance and Productivity Agenda

Overview – A signal is a reactive primitive: a wrapper around a value that notifies interested consumers when that value changes – The signal concept is a lot simpler than RxJS (= streamlined APIs) – Signals form the basis for a new, more effective change detection system in Angular that could eventually replace Zone.js (= performance improvement) – Works great with ChangeDetectionStrategy.OnPush The New Angular Maximizing Performance and Productivity Signals

API – Writable Signals const count = signal(0); count.set(3); – Computed Signals const doubleCount = computed(() => count() * 2); – Effects effect(() => console.log(`The count is: ${doubleCount()}`)); The New Angular Maximizing Performance and Productivity Signals https://angular.dev/guide/signals

RxJS Interop – Convert observable to signal counter$ = interval(1000); counter = toSignal(this.counter$, {initialValue: 0}); – Convert signal to observable counter = signal(0); counter$ = toObservable(this.counter); – takeUntilDestroyed() The New Angular Maximizing Performance and Productivity Signals https://angular.dev/guide/signals/rxjs-interop

OLD Zone.js-based Change Detection The New Angular Maximizing Performance and Productivity Signals current (global) zone NgZone Angular boot onclick setTimeout Detect changes Detect changes CHANGE {{ binding }} {{ binding }} {{ binding }} {{ binding }}

POSSIBLE Future Change Detection The New Angular Maximizing Performance and Productivity Signals CHANGE {{ binding }} {{ signal() }} {{ binding }} {{ binding }}

Signal-based Components (since Angular 17.1) @Component({ selector: "counter", standalone: true, template: "{{ value }}", }) export class CounterComponent { @Input() value = 0; @Input({ required: true }) value2!: number; } @Component({ selector: "counter", standalone: true, template: "{{ value() }}", }) export class CounterComponent { value = input(0); value2 = input.required(); } The New Angular Maximizing Performance and Productivity Signals https://blog.angular-university.io/angular-signal-inputs/ OLD NEW

Signal-based Components (since Angular 17.2) @Component({ selector: "counter", standalone: true, template: "{{ value }}", }) export class CounterComponent { @Input({ required: true }) value = 0; @Output() valueChange = new EventEmitter(); } @Component({ selector: "counter", standalone: true, template: "{{ value() }}", }) export class CounterComponent { value = model.required(); } The New Angular Maximizing Performance and Productivity Signals https://blog.angular-university.io/angular-signal-inputs/ OLD NEW

Signal-based Components (since Angular 17.3) @Component({ selector: "counter", standalone: true, template: "", }) export class CounterComponent { @Output() count = new EventEmitter(); } @Component({ selector: "counter", standalone: true, template: "", }) export class CounterComponent { count = output(); } The New Angular Maximizing Performance and Productivity Signals OLD NEW

Signal-based Components (since Angular 17.2) @ViewChild(MyComponent) a!: MyComponent; @ViewChilren(MyComponent) b!: QueryList; @ContentChild(MyComponent) c!: MyComponent; @ContentChildren(MyComponent) d!: QueryList; a = viewChild(MyComponent); b = viewChildren(MyComponent); c = contentChild(MyComponent); d = contentChildren(MyComponent); The New Angular Maximizing Performance and Productivity Signals OLD NEW

Zoneless Change Detection (since Angular 18.0) bootstrapApplication(AppComponent, { providers: [ provideExperimentalZonelessChangeDetection(), ], }); The New Angular Maximizing Performance and Productivity Signals NEW

NgRx Signal Store – Reactive state management solution based on Signals – Simple and lightweight – Package: @ngrx/signals – Replacement for component store and entity adapter – Function-based, but can be class-based The New Angular Maximizing Performance and Productivity Signals https://ngrx.io/guide/signals

Maturity – effect(), RxJS interop, Signal-based components, and zoneless change detection are still in developer preview (as of Angular 18.0.0) – @ngrx/signals is still in developer preview (as of version 17.2.0) The New Angular Maximizing Performance and Productivity Signals

Migration Strategy – Why? You should migrate to Signals, as they improve performance and API simplicity. – When? You should write new components based on Signals and migrate older components if time permits. Currently, there’s no hurry: RxJS and the traditional ways in Angular won’t go away anytime soon, and some Signal APIs and frameworks are still in developer preview. – How? Manual effort required, no automated migration available. (Could probably be handled by GenAI.) The New Angular Maximizing Performance and Productivity Signals

Signals Standalone Components and APIs Built-in Control Flow and Deferrable Views Server-Side Rendering, esbuild and Vite The New Angular Maximizing Performance and Productivity Agenda

The New Angular Maximizing Performance and Productivity NgModules UI-related components (BookModule) UI-related components (TodoModule) Logic/ infrastructure components (BookModule) Logic/ infrastructure components (TodoModule) Components Directives Pipes High-Level Services Low-Level Services

@NgModule({ declarations: [AppComponent, HomeComponent, MenuComponent], imports: [BrowserModule], providers: [DataService], bootstrap: [AppComponent], }) export class AppModule { } The New Angular Maximizing Performance and Productivity NgModules

The problem with modules… @Component({ selector: 'app-my', template: `{{ item.name | myPipe }}`, }) export class MyComponent { @Input({ required: true }) items!: Item[]; } Question: Where does appTooltip and myPipe come from? The New Angular Maximizing Performance and Productivity NgModules OLD

@Component({ selector: 'app-my', template: `{{ item.name | myPipe }}`, standalone: true, imports: [NgFor, TooltipDirective, MyPipe] }) export class MyComponent { @Input({ required: true }) items!: Item[]; } The New Angular Maximizing Performance and Productivity Standalone Components NEW

Interoperability with NgModules – Standalone components/directives/pipes can’t be part of NgModules – When used in non-standalone components, it needs to be imported @NgModule({ declarations: [MyStandaloneComponent], imports: [MyStandaloneComponent], }) export const MyModule {} The New Angular Maximizing Performance and Productivity Standalone Components

Interoperability with NgModules @Component({ selector: 'app-my', template: `{{ item.name | myPipe }}`, standalone: true, imports: [CommonModule, TooltipModule, PipeModule] }) export class MyComponent { @Input({ required: true }) items!: Item[]; } The New Angular Maximizing Performance and Productivity Standalone Components

Web Components Streamlined standalone API simplifies the creation of web components from Angular components Web components can be used in any context (not only Angular apps) ⚠ Problem: Zone.js is still used for change detection, the Angular team is actively working on making this optional The New Angular Maximizing Performance and Productivity Standalone Components

The New Angular Maximizing Performance and Productivity

Folder Structure Modules main.ts app/app-routing.module.ts app/app.module.ts Standalone Apps main.ts app/app.routes.ts app/app.config.ts The New Angular Maximizing Performance and Productivity Standalone Applications OLD NEW

Bootstrap API Modules import { platformBrowser } from '@angular/platform-browser'; import { AppModule } from './app/app.module'; platformBrowser() .bootstrapModule(AppModule) .catch(e => console.error(e)); Standalone Apps import { bootstrapApplication } from '@angular/platform-browser'; import { AppComponent } from './app/app.component'; bootstrapApplication(AppComponent) .catch(e => console.error(e)); The New Angular Maximizing Performance and Productivity Standalone Applications OLD NEW

Providers Modules @NgModule({ imports: [ BrowserModule, RouterModule.forRoot(routes), HttpClientModule ] }) export class AppModule { } Standalone Apps export const appConfig: ApplicationConfig = { providers: [ provideRouter(routes), provideHttpClient(), // fallback for modules: importProvidersFrom (TranslateModule) ] }; The New Angular Maximizing Performance and Productivity Standalone Applications OLD NEW

Environment Injectors Modules @NgModule({ providers: [{ provide: PhotosService, useClass: CustomPhotosService, }] }) export class MyModule { constructor() { // My logic } } Standalone Apps createEnvironmentInjector([ { provide: PhotosService, useClass: CustomPhotosService }, { provide: ENVIRONMENT_INITIALIZER, useValue: () => {/* My logic */} } ]); The New Angular Maximizing Performance and Productivity Standalone Applications OLD NEW

Migration Strategy – Maturity: Standalone components and APIs are fully stable. – Why? Standalone components and APIs improve developer experience and prepare your codebase for upcoming Angular features. – When? New projects should be started using standalone APIs, new components should be added as standalone components (default since version 17), NgModules and standalone are interoperable. – Existing projects should be migrated as soon as possible, new parts should be added using standalone components/APIs. – ⚠ Some ng add/ng update integrations may not work with standalone workspaces. The New Angular Maximizing Performance and Productivity Standalone Components & APIs

How? – Migration can be partly automated – Manual changes will be required – Effort for mid-size projects: 4–8 hours – No functional difference – ⚠ Changes to the project setup may lead to the migration to break – ⚠ Replacements in unit tests may be incorrect – ⚠ Migration does not introduce the new folder structure (app config) The New Angular Maximizing Performance and Productivity Standalone Components & APIs

Migration ng g @angular/core:standalone The New Angular Maximizing Performance and Productivity Standalone Components & APIs

Signals Standalone Components and APIs Built-in Control Flow and Deferrable Views Server-Side Rendering, esbuild and Vite The New Angular Maximizing Performance and Productivity Agenda

If Item not found! @if (item) { } @else { Item not found! } The New Angular Maximizing Performance and Productivity Built-in Control Flow OLD NEW https://angular.dev/essentials/conditionals-and-loops#if-block

Motivation – Control flow is built into the renderer, so you don’t have to import the structural directives (e.g., CommonModule, NgIf). – Dummy DOM elements such as are no longer needed. – The structural directive syntax (e.g., *ngIf) is not very common. – Better performance (up to 90% for @for), no longer tied to Zone.js. – Improve developer experience when dealing with common scenarios, such as “else” blocks, empty lists or deferring loading certain content. – ⚠ But: Built-in control flow is not extensible, in contrast to structural directives (e.g., *ngxPermission). The New Angular Maximizing Performance and Productivity Built-in Control Flow https://angular.dev/guide/templates/control-flow https://blog.angular.io/introducing-angular-v17-4d7033312e4b

Switch Case A. Default case. @switch (condition) { @case (caseA) { Case A. } @default { Default case. } } The New Angular Maximizing Performance and Productivity Built-in Control Flow OLD NEW https://angular.dev/guide/templates/control-flow#switch-block---selection

For

{{ item.name }}

No items.

@for (item of items; track item.name) {

{{ item.name }}

} @empty {

No items.

} The New Angular Maximizing Performance and Productivity Built-in Control Flow OLD NEW https://angular.dev/essentials/conditionals-and-loops#for-block

Migration Strategy – Maturity: The built-in control flow is fully stable. – Why? Optimizes developer experience for common scenarios and improves performance (Zone.js, mandatory tracking in for loops) – When? Start using control flow now and migrate your codebase as soon as possible. Otherwise, keep using structural directives and migrate later. – Supported by current versions of WebStorm, VS Code and Prettier. – ⚠ But: The syntax does not match the HTML standard and may lead to problems with older IDE versions or tooling that is not aware of it. The New Angular Maximizing Performance and Productivity Built-in Control Flow

How? – Migration can be automated – Target path can be specified (allowing a step-by-step migration) – Allows formatting affected files – Removes CommonModule/structural directive imports from component class – Manual changes likely required – Effort for mid-size projects: < 1 hour – No functional changes The New Angular Maximizing Performance and Productivity Built-in Control Flow

How? – ⚠ @for tracks the count variable by default (not necessarily best for performance) – ⚠ The built-in control flow does not support some rarely used features that were previously possible (e.g., *ngFor collection aliasing, multiple *ngIf aliases, …). These usages must be changed before running the migration. – ⚠ Template reformatting does not use Prettier The New Angular Maximizing Performance and Productivity Built-in Control Flow

Migration ng g @angular/core:control-flow The New Angular Maximizing Performance and Productivity Built-in Control Flow

Motivation – Takes lazy loading a step further by bringing it to the template level, which can improve the load time performance of your application. – Loads a (large/rarely used) view only based on a certain trigger (e.g., when the template enters the viewport, the device is idle, …). – Everything uses template magic, enabled by the new @defer block. – Offers helpers like @placeholder (while the content is being loaded), or @error when the content fails to load. – An example for a feature that is only accessible via the new syntax. The New Angular Maximizing Performance and Productivity Deferrable Views

Examples @defer (on viewport) { } @placeholder { } @error { Failed to load the calendar! } The New Angular Maximizing Performance and Productivity Deferrable Views https://angular.dev/guide/defer

Signals Standalone Components and APIs Built-in Control Flow and Deferrable Views Server-Side Rendering, esbuild and Vite The New Angular Maximizing Performance and Productivity Agenda

Motivation – Server-side rendering (SSR) renders the application on the server, significantly improving load time performance – Prerendering/static site generation (SSG) renders all static HTML files during build time, improving server response time – Hydration allows client-side Angular to reattach to the server- rendered DOM nodes during launch, improving client-side load time – Partial Hydration (implementation in progress) renders the content of a @defer block on the server and reattaches on the client. The New Angular Maximizing Performance and Productivity Server-Side Rendering

Motivation

In Angular 17 – SSR is now fully integrated with Angular and includes SSR, prerendering, and hydration – Angular Universal is no longer offered as a separate library – For new projects, SSR can be easily enabled (e.g., ng new --ssr) – Existing projects first have to switch to the new application builder and update their configuration The New Angular Maximizing Performance and Productivity Server-Side Rendering

Caveats – ⚠ Setting up SSR with authentication is hard, SSG may be impossible. – ⚠ Custom or Noop Zone.js are not yet supported. – ⚠ Angular i18n with hydration is not yet supported. – ⚠ When the Angular Service Worker is used, SSR is only used on the first visit. – ⚠ All components must be built for hydration. – ⚠ Libraries that depend on DOM manipulation (D3 charts, grids, …) may break hydration. Skipping hydration is possible via ngSkipHydration, but you’ll lose the advantages of hydration. The New Angular Maximizing Performance and Productivity Server-Side Rendering

Motivation The JavaScript ecosystem has advanced and new (and significantly faster) build tools have arrived. The New Angular Maximizing Performance and Productivity esbuild and Vite https://esbuild.github.io/

Motivation – Significantly faster build times (initial/incremental) – Compatibility with native ECMAScript Modules (ESM) and the modern JavaScript ecosystem – Hot module replacement (HMR) support for styles (performance improvement) The New Angular Maximizing Performance and Productivity esbuild and Vite https://blog.angular.io/introducing-angular-v17-4d7033312e4b

Motivation – Maturity: New apps created from Angular 17 onwards will automatically use the application builder – Why? Significantly faster build times, modern JavaScript – When? The existing Webpack-based build system is still stable. Old apps will not be migrated automatically. As Angular will move on, you should migrate as time permits. – How? Aim for application; if that is not possible, try browser-esbuild. Just replace the builders in angular.json and see if the build works. If not, investigate and estimate the effort. The New Angular Maximizing Performance and Productivity esbuild and Vite

Migration ng update @angular/cli --name use-application-builder The New Angular Maximizing Performance and Productivity esbuild and Vite

The “Angular Renaissance” is real Notable advancements while being backwards compatible Increased build/runtime performance and developer experience Keep your users and developers happy Angular 17.1+ apps will look significantly different to previous versions Avoid technical debt, migrate now The New Angular Maximizing Performance and Productivity Summary

Thank you for your kind attention! Christian Liebel @christianliebel [email protected]