Angular basics

Angular basics.md

Components vs Directives

• what's the scope of usage of each one, when to chose what

Directives

• structural vs non-structural
• *ngIf, *ngFor, ngSwitch, *ngTemplateOutlet, *ngComponentOutlet
• ng-template, ng-container, ng-content elements
• performance optimisations for *ngFor

Pipes

• pure vs non-pure
• built-in pipes
• async pipe

Components

• Lifecycle hooks (onInit, onDestroy, onChanges) what to use and when, difference
• Constructor vs OnInit in components
• @Input, @Output, @Attribute decorators
• @HostBinding, @HostListener
• @ViewChild(ren), @ContentChild(ren)
• view events binding (e.g. click, change)

Dependency injection

• @Injectable, @Inject decorators
• Module providers (global), component-scoped providers
• What is InjectionToken
• FactoryProvider, ClassProvider

Modules

• lazy-loaded vs normal modules vs root module
• @NgModule: imports, exports, declarations, entryComponents, providers properties
• Splitting app to modules by features

Routing

• Defining routes & child routes, route params, route path wildcards
• Router outlet directive
• Programmatically navigating by url, by params, relative to current route
• routerLink, routerLinkParams directives
• RouterModule.forRoot vs .forChild
• Router events
• Resolves, Guards, CanActivate(Child), CanLoad
• Route data dictionary, params, query params dictionary
• Accessing currently activated route in component
• What is ActivatedRouteSnapshot?

RxJS

• https://rxmarbles.com/ - see for visual explanation
• https://www.learnrxjs.io/ - see for examples
• what is rxjs and observable pattern, how it works
• Subject types
• what is EventEmitter?
• most often used operators: map, filter, forkJoin, catchError, switchMap, concat*, merge*, from, of, first, share*, partition, take*, skip*
• how to create observable
• hot vs cold observable
• how and why to unsubscribe from observable

Reactive forms

• FormGroup, FormControl, FormArray, FormBuilder
• reactive vs template-driven forms
• how to create form and bind it to view
• subscribing & reacting on control value changes
• validation and validators, built-in & writing custom
• showing validation messages depending on control's state
• NgForm, FormGroup, FormGroupName, FormControl, FormControlName directives
• The ControlValueAccessor interface and implementing custom form control (e.g file upload control)

HttpClient & pipeline

• Response & Request objects
• Response & request types
• Handling errors
• HttpInterceptor concept