Angular is a comprehensive web application framework that provides a complete development platform for building scalable, maintainable web applications with component-based architecture, dependency injection, reactive forms, routing, HTTP client, and extensive tooling.
npx @tessl/cli install tessl/npm-angular@20.2.0Angular is a comprehensive web application framework that provides a complete development platform for building scalable, maintainable web applications. It features component-based architecture with dependency injection, reactive forms, powerful routing system, HTTP client with interceptors, animations, testing utilities, and CLI tools for development workflow.
npm install @angular/core @angular/common @angular/router @angular/formsimport { Component, Injectable, NgModule, inject } from '@angular/core';
import { Router, ActivatedRoute } from '@angular/router';
import { HttpClient } from '@angular/common/http';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';import { Component, inject } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { FormBuilder, Validators } from '@angular/forms';
@Component({
selector: 'app-user',
template: `
<form [formGroup]="userForm" (ngSubmit)="onSubmit()">
<input formControlName="name" placeholder="Name">
<input formControlName="email" placeholder="Email">
<button type="submit" [disabled]="userForm.invalid">Submit</button>
</form>
`
})
export class UserComponent {
private http = inject(HttpClient);
private fb = inject(FormBuilder);
userForm = this.fb.group({
name: ['', [Validators.required, Validators.minLength(2)]],
email: ['', [Validators.required, Validators.email]]
});
onSubmit() {
if (this.userForm.valid) {
this.http.post('/api/users', this.userForm.value)
.subscribe(response => console.log('User saved:', response));
}
}
}Angular is built around several key architectural concepts:
Core framework functionality including components, dependency injection, change detection, lifecycle hooks, and signals-based reactivity.
// Component decoration and lifecycle
function Component(options: ComponentOptions): ClassDecorator;
function Injectable(options?: InjectableOptions): ClassDecorator;
function NgModule(options: NgModuleOptions): ClassDecorator;
// Dependency injection
function inject<T>(token: Type<T> | InjectionToken<T>): T;
// Signals and reactivity
function signal<T>(initialValue: T): WritableSignal<T>;
function computed<T>(computation: () => T): Signal<T>;
function effect(effectFn: () => void): EffectRef;
// Component creation and lifecycle
interface OnInit {
ngOnInit(): void;
}
interface OnDestroy {
ngOnDestroy(): void;
}Client-side routing system for single-page applications with route guards, lazy loading, and navigation management.
function provideRouter(routes: Routes, ...features: RouterFeature[]): Provider[];
class Router {
navigate(commands: any[], extras?: NavigationExtras): Promise<boolean>;
navigateByUrl(url: string | UrlTree, extras?: NavigationBehaviorOptions): Promise<boolean>;
}
interface Route {
path?: string;
component?: Type<any>;
loadComponent?: () => Type<any> | Observable<Type<any>> | Promise<Type<any>>;
children?: Routes;
canActivate?: any[];
}Form handling system with validation, reactive updates, and type safety for building complex forms and user input handling.
class FormBuilder {
group(controls: {[key: string]: any}, options?: AbstractControlOptions): FormGroup;
control(formState: any, validatorOrOpts?: ValidatorFn | AbstractControlOptions): FormControl;
array(controls: AbstractControl[], validatorOrOpts?: ValidatorFn | AbstractControlOptions): FormArray;
}
class FormGroup extends AbstractControl {
get(path: Array<string | number> | string): AbstractControl | null;
addControl(name: string, control: AbstractControl): void;
removeControl(name: string): void;
}
class Validators {
static required(control: AbstractControl): ValidationErrors | null;
static email(control: AbstractControl): ValidationErrors | null;
static min(min: number): ValidatorFn;
static max(max: number): ValidatorFn;
}HTTP client for making API requests with interceptors, error handling, and type safety for backend communication.
function provideHttpClient(...features: HttpFeature[]): Provider[];
class HttpClient {
get<T>(url: string, options?: HttpOptions): Observable<T>;
post<T>(url: string, body: any, options?: HttpOptions): Observable<T>;
put<T>(url: string, body: any, options?: HttpOptions): Observable<T>;
delete<T>(url: string, options?: HttpOptions): Observable<T>;
}
interface HttpInterceptor {
intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>>;
}Shared utilities, directives, pipes, and common functionality used across Angular applications.
// Common directives
class NgIf {
ngIf: any;
ngIfThen?: TemplateRef<NgIfContext<T>>;
ngIfElse?: TemplateRef<NgIfContext<T>>;
}
class NgFor {
ngForOf: NgIterable<T>;
ngForTemplate: TemplateRef<NgForOfContext<T>>;
ngForTrackBy?: TrackByFunction<T>;
}
// Common pipes
class DatePipe implements PipeTransform {
transform(value: Date | string | number, format?: string, timezone?: string, locale?: string): string | null;
}
class AsyncPipe implements PipeTransform {
transform<T>(obj: Observable<T> | Promise<T>): T | null;
}Animation framework for creating smooth transitions, complex animations, and interactive effects.
function trigger(name: string, definitions: AnimationMetadata[]): AnimationTriggerMetadata;
function state(name: string, styles: AnimationStyleMetadata): AnimationStateMetadata;
function transition(stateChangeExpr: string, steps: AnimationMetadata[]): AnimationTransitionMetadata;
function animate(timings: string | number, styles?: AnimationStyleMetadata): AnimationAnimateMetadata;
class AnimationBuilder {
build(animation: AnimationMetadata | AnimationMetadata[]): AnimationFactory;
}Comprehensive testing utilities for unit testing, integration testing, and end-to-end testing of Angular applications.
class TestBed {
static configureTestingModule(moduleDef: TestModuleMetadata): TestBedStatic;
static createComponent<T>(component: Type<T>): ComponentFixture<T>;
static inject<T>(token: Type<T> | InjectionToken<T>): T;
}
interface ComponentFixture<T> {
componentInstance: T;
debugElement: DebugElement;
detectChanges(): void;
whenStable(): Promise<any>;
}
function fakeAsync(fn: Function): (...args: any[]) => any;
function tick(millis?: number): void;// Core interfaces
interface ComponentOptions {
selector?: string;
template?: string;
templateUrl?: string;
styleUrls?: string[];
styles?: string[];
providers?: Provider[];
viewProviders?: Provider[];
changeDetection?: ChangeDetectionStrategy;
encapsulation?: ViewEncapsulation;
}
interface InjectableOptions {
providedIn?: Type<any> | 'root' | 'platform' | 'any' | null;
}
interface NgModuleOptions {
declarations?: Array<Type<any> | any[]>;
imports?: Array<Type<any> | ModuleWithProviders<{}> | any[]>;
providers?: Provider[];
bootstrap?: Array<Type<any> | any[]>;
exports?: Array<Type<any> | any[]>;
}
// Signal types
interface Signal<T> {
(): T;
}
interface WritableSignal<T> extends Signal<T> {
set(value: T): void;
update(updateFn: (value: T) => T): void;
}
// Type aliases for common patterns
type Provider = TypeProvider | ValueProvider | ClassProvider | ExistingProvider | FactoryProvider;
type Routes = Route[];
type ValidatorFn = (control: AbstractControl) => ValidationErrors | null;
type TrackByFunction<T> = (index: number, item: T) => any;
// Enums
enum ChangeDetectionStrategy {
OnPush = 0,
Default = 1
}
enum ViewEncapsulation {
Emulated = 0,
None = 2,
ShadowDom = 3
}