Interview Q&A

Short answer: synchronously in Angular? Use Async Validators returning Observable<ValidationErrors | null>. ✅ function uniqueUsernameValidator(service: UserService): syncValidatorFn { return (control: AbstractControl): Observable<ValidationErrors | null> => { return service.checkUsername(control.value).pipe( map(isTaken => (isTaken ? {… uniqueUsername: true } :…… null)) ); }; } // Usage: new FormControl('', null,…

Explain a bit more

uniqueUsernameValidator(this.userService)); synchronously in Angular? synchronously in Angular? Use Async Validators returning Observable<ValidationErrors | null>. ✅

Example code

function uniqueUsernameValidator(service: UserService): syncValidatorFn { return (control: AbstractControl): Observable<ValidationErrors | null> => { return service.checkUsername(control.value).pipe( map(isTaken => (isTaken ? {… uniqueUsername: true } :… null)) ); }; } // Usage: new FormControl('', null, uniqueUsernameValidator(this.userService)); synchronously in Angular? synchronously in Angular? Use Async Validators returning Observable<ValidationErrors | null>. ✅ Example: function uniqueUsernameValidator(service: UserService): syncValidatorFn { return (control: AbstractControl): Observable<ValidationErrors | null> => { return service.checkUsername(control.value).pipe( map(isTaken => (isTaken ? { uniqueUsername: true } :… null)) ); }; } // Usage: new FormControl('', null, uniqueUsernameValidator(this.userService)); synchronously in Angular? Use Async Validators returning Observable<ValidationErrors | null>. ✅ Example: function uniqueUsernameValidator(service: UserService): syncValidatorFn { return (control: AbstractControl): Observable<ValidationErrors | null> => { return service.checkUsername(control.value).pipe( map(isTaken => (isTaken ? { uniqueUsername: true } : null)) ); }; } // Usage: new FormControl('', null, uniqueUsernameValidator(this.userService));

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Implement a global error handler by extending Angular’s ErrorHandler class: @Injectable() export class GlobalErrorHandler implements ErrorHandler { handleError(error: any) { // log to server or show user notification console.error('Global error:', error); } } Provide it in your AppModule: providers: [{ provide: ErrorHandler, useClass: GlobalErrorHandler }] Can also use HTTP interceptors to catch API errors.

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: pplication? Implement a global error handler by extending Angular’s ErrorHandler class: @Injectable() export class GlobalErrorHandler implements ErrorHandler { handleError(error: any) { // log to server or show user notification console.error('Global error:', error); } } Provide it in your AppModule: providers: [{ provide: ErrorHandler,… useClass:……… pplication? pplication? Implement a global error handler by…

Explain a bit more

extending Angular’s ErrorHandler class: @Injectable() export class GlobalErrorHandler implements ErrorHandler { handleError(error: any) { // log to server or show user notification console.error('Global error:', error); } } Provide it in your AppModule: providers: [{ provide: ErrorHandler, useClass:… pplication? Implement a global error handler by extending Angular’s ErrorHandler class: @Injectable() export class GlobalErrorHandler implements ErrorHandler { handleError(error: any) { // log to server or show user notification console.error('Global error:', error); } } Provide it in your AppModule: providers: [{ provide:… pplication?…

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Create a class with the @Pipe decorator implementing PipeTransform. Implement a transform() method with your logic. Example: @Pipe({ name: 'exclaim' }) export class ExclaimPipe implements PipeTransform { transform(value: string): string { return value + '!!!';

Example code

}
} Use in template: <p>{{ 'Hello' | exclaim }}</p> <!-- Outputs: Hello!!! -->

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: AOT compiles templates before runtime, improving startup performance. Enable via: ng build --aot Usually enabled automatically with --prod. Can be configured in angular.json: "configurations": { "production": { "aot": true }

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Angular uses the fileReplacements option in angular.json.

Explain a bit more

You create environment files like environment.ts and environment.prod.ts. During build, Angular replaces the environment file based on the target configuration. Example in angular.json: "configurations": { "production": { "fileReplacements": [ { "replace": "src/environments/environment.ts", "with": "src/environments/environment.prod.ts" } } } Allows different API endpoints, debug flags, or configurations per environment. Best Practices

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Angular modules (NgModules) are containers that group related components, directives, pipes, and services. Purpose: Organize code Enable lazy loading Manage dependencies

Example code

@NgModule({ declarations: [LoginComponent], imports: [CommonModule, FormsModule], exports: [LoginComponent] }) export class AuthModule {} Real-Time Example: AuthModule for login and registration AdminModule for dashboard, user management

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use the reset() method on FormGroup or NgForm.

Explain a bit more

✅ Examples: this.profileForm.reset(); myForm.resetForm(); You can also pass default values: this.profileForm.reset({ firstName: 'John', lastName: '' }); Summary Table: Concept Template-Driven Reactive Setup Use FormsModule, ngModel Use ReactiveFormsModule, FormGroup Validation Template-driven (HTML attrs) Programmatic with Validators Form Definition Implicit Explicit in TypeScript Custom Validation Limited Full control via functions Async Validation Not supported Supported with AsyncValidators Testing Harder Easier and more robust FormBuilder N/A Simplifies form creation Change Detection & Performance Optimization

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Protractor is built on WebDriverJS for Angular E2E tests. Write test specs using Jasmine syntax. Run tests against a running Angular app. Example test: describe('App E2E Test', () => { it('should display welcome message', () => { browser.get('/'); expect(element(by.css('h1')).getText()).toEqual('Welcome'); }); }); Run with: ng e2e

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Test form validity by setting control values and checking validity state.

Example code

it('should mark form invalid when empty', () => { component.form.controls['email'].setValue(''); expect(component.form.valid).toBeFalse(); }); it('should mark form valid with correct email', () => { component.form.controls['email'].setValue('test@example.com'); expect(component.form.valid).toBeTrue(); }); Advanced Angular Topics

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Offload heavy computations or tasks to: Web Workers to run in background threads. ngZone.runOutsideAngular() to prevent triggering change detection unnecessarily. Use RxJS operators like debounce, throttle to optimize async streams. Break large tasks into smaller chunks. Miscellaneous Angular Concepts

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: ngular? Test form validity by setting control values and checking validity state. it('should mark form invalid when empty', () => { component.form.controls['email'].setValue(''); expect(component.form.valid).toBeFalse(); }); it('should mark form valid with correct email', () => {… component.form.controls['email'].setValue('test@example.com');…… expect(component.form.valid).toBeTrue(); }); dvanced Angular Topics…

Explain a bit more

ngular? ngular? Test form validity by setting control values and checking validity state.

Example code

it('should mark form invalid when empty', () => { component.form.controls['email'].setValue(''); expect(component.form.valid).toBeFalse(); }); it('should mark form valid with correct email', () => {… component.form.controls['email'].setValue('test@example.com');… expect(component.form.valid).toBeTrue(); }); dvanced Angular Topics ngular? ngular? Test form validity by setting control values and checking validity state. Example: it('should mark form invalid when empty', () => { component.form.controls['email'].setValue(''); expect(component.form.valid).toBeFalse(); }); it('should mark form valid with correct email', () => { component.form.controls['email'].setValue('test@example.com');… expect(component.form.valid).toBeTrue(); }); dvanced Angular Topics ngular? Test form validity by setting control values and checking validity state. Example: it('should mark form invalid when empty', () => { component.form.controls['email'].setValue(''); expect(component.form.valid).toBeFalse(); }); it('should mark form valid with correct email', () => { component.form.controls['email'].setValue('test@example.com'); expect(component.form.valid).toBeTrue(); }); dvanced Angular Topics

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.