Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Christian Liebel @christianliebel Consultant Angular 18

Hello, it’s me. Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Christian Liebel X: @christianliebel Email: christian.liebel @thinktecture.com Angular & PWA Slides: thinktecture.com /christian-liebel

Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren “Angular Renaissance”

Control state change events const nameControl = new FormControl('name', Validators.required); nameControl.events.subscribe(event => { // process the individual events }); Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Angular 18 https://blog.angular.dev/angular-v18-is-now-available-e79d5ac0affe#b6b1

Route redirection functions const routes: Routes = [{ path: "old-user-page", redirectTo: ({ queryParams }) => { return queryParams["foo"] ? `/user/${queryParams["foo"]}` : `/not-found`; }, }]; Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Angular 18 https://blog.angular.dev/angular-v18-is-now-available-e79d5ac0affe#7fb8

Fallback content for @Component({ selector: 'app-profile', template: ` Hello Unknown user `, }) export class Profile {} Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Angular 18 https://blog.angular.dev/angular-v18-is-now-available-e79d5ac0affe#2a2b

Material 3 Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Angular 18

TypeScript Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Angular 18

Signals Standalone Components and APIs Built-in Control Flow and Deferrable Views Server-Side Rendering, esbuild and Vite Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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 Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals

OLD Zone.js-based Change Detection Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals current (global) zone NgZone Angular boot onclick setTimeout Detect changes Detect changes {{ binding }} {{ binding }} {{ binding }} {{ binding }}

POSSIBLE Future Change Detection Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals {{ binding }} {{ signal() }} {{ binding }} {{ binding }}

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()}`)); Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals https://angular.dev/guide/signals

Don't Use Effects and What To Do Instead Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals https://www.youtube.com/watch?v=aKxcIQMWSNU

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() Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals https://angular.dev/guide/signals/rxjs-interop

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(); } Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals https://blog.angular-university.io/angular-signal-inputs/

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(); } Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals https://blog.angular-university.io/angular-signal-inputs/

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(); } Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals

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); Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals

Zoneless Change Detection (since Angular 18.0) bootstrapApplication(AppComponent, { providers: [ provideExperimentalZonelessChangeDetection(), ], }); Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals

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 – Stable with NgRx 18 Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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 18.2.4) – Used by YouTube Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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.) Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Signals

Signals Standalone Components and APIs Built-in Control Flow and Deferrable Views Server-Side Rendering, esbuild and Vite Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Agenda

Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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 { } Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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? Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren NgModules

@Component({ selector: 'app-my', template: `{{ item.name | myPipe }}`, standalone: true, imports: [NgFor, TooltipDirective, MyPipe] }) export class MyComponent { @Input({ required: true }) items!: Item[]; } Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Standalone Components

Default with Angular 19 @Component({ selector: 'app-my', template: '', standalone: false }) export class MyComponent { } Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Standalone Components

Lazy Loading export const ROUTES: Route[] = [ { path: 'admin', loadComponent: () => import('./admin/panel.component') .then(mod => mod.AdminPanelComponent), providers: [MyService] }, // … ]; Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Standalone Components https://angular.io/guide/standalone-components#lazy-loading-a-standalone-component

Lazy Loading Multiple Routes export const ROUTES: Route[] = [ {path: 'admin', loadChildren: () => import('./admin/routes')}, // … ]; export default [ {path: 'home', component: AdminHomeComponent}, {path: 'users', component: AdminUsersComponent}, // … ] as Route[]; Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Standalone Components https://angular.io/guide/standalone-components#lazy-loading-many-routes-at-once

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 {} Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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[]; } Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Standalone Components

Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren

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 Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Standalone Applications

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)); Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Standalone Applications

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) ] }; Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Standalone Applications

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. Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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) Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Standalone Components & APIs

Migration ng g @angular/core:standalone Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Standalone Components & APIs

Signals Standalone Components and APIs Built-in Control Flow and Deferrable Views Server-Side Rendering, esbuild and Vite Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Agenda

If Item not found! @if (item) { } @else { Item not found! } Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Built-in Control Flow 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). Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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. } } Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Built-in Control Flow 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.

} Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Built-in Control Flow https://angular.dev/essentials/conditionals-and-loops#for-block

Migration Strategy – Maturity: The built-in control flow is fully stable in Angular 18. – 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. Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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 Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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 Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Built-in Control Flow

Migration ng g @angular/core:control-flow Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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. – Fully stable in Angular 18 Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Deferrable Views

Examples @defer (on viewport) { } @placeholder { } @error { Failed to load the calendar! } Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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 Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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. Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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 – Angular Material 18: all components support hydration Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Server-Side Rendering

Caveats – Setting up SSR with authentication is hard, SSG may be impossible. – Custom or Noop Zone.js are 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. Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Server-Side Rendering

Partial Hydration (hypothetical syntax!) @defer (render on server; on viewport) { } @placeholder { } @error { Failed to load the calendar! } Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Server-Side Rendering https://angular.dev/guide/defer

Motivation The JavaScript ecosystem has advanced and new (and significantly faster) build tools have arrived. Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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) Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren esbuild and Vite https://blog.angular.io/introducing-angular-v17-4d7033312e4b

New Builders browser-esbuild More compatible, drop-in replacement for “browser” builder application Integrated SSR, requires code changes when SSR was used, requires configuration changes "architect": { "build": { "builder": "@angular-devkit/build-angular:application", "options": { "outputPath": { "base": "dist/my-app" }, "index": "src/index.html", "polyfills": [ "zone.js" ], "tsConfig": "tsconfig.app.json", "assets": [ "src/favicon.ico", "src/assets", Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren esbuild and Vite https://angular.dev/tools/cli/build-system-migration

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. Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren esbuild and Vite

Migration ng update @angular/cli --name use-application-builder Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren 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 Angular 18 Neue Features optimal nutzen und Bestandsprojekte effizient migrieren Summary

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