Interview Questions and Answers

Example:

const observable = new Observable(observer => { observer.next('Hello'); });

Example:

const observable = new Observable(observer => { observer.next('First'); observer.next('Second'); });

Example:

const observer = { next: value => console.log(value), error: err => console.error(err), complete: () => console.log('Completed') };

Example:

const pluckedObservable = sourceObservable.pipe(pluck('name'));

Example:

const distinctObservable = observable.pipe(distinctUntilChanged());

Example:

const intervalObservable = interval(1000);

Example:

const takenObservable = observable.pipe(take(3));

Example:

const modifiedObservable = observable.pipe(map(value => value.toUpperCase()));

Example:

const modifiedObservable = observable.pipe(map(value => value * 2));

Example:

const modifiedObservable = observable.pipe(mergeMap(value => of(value, value * 2)));

Example:

const filteredObservable = observable.pipe(filter(value => value > 5));

Example:

import { map, filter } from 'rxjs/operators'; const modifiedObservable = observable.pipe(map(value => value * 2), filter(value => value > 5));

Example:

const switchedObservable = observable.pipe(switchMap(value => of(value, value * 2)));

Example:

const subject = new Subject(); subject.next('First value'); subject.subscribe(value => console.log(value));

Example:

const concatenatedObservable = observable.pipe(concatMap(value => of(value, value * 2)));

Example:

const errorHandledObservable = observable.pipe(catchError(err => of('Error handled:', err)));

Example:

const zippedObservable = zip(observable1, observable2, (value1, value2) => value1 + value2);

Example:

const bufferedObservable = observable.pipe(bufferTime(1000));

Example:

const throttledObservable = inputObservable.pipe(throttleTime(300));

Example:

const combinedObservable = combineLatest(observable1, observable2, (value1, value2) => value1 + value2);

Example:

const deferredObservable = defer(() => of('Deferred value'));

Example:

const subject = new Subject(); observable.subscribe(subject);

Example:

Cold: const coldObservable = new Observable(...); Hot: const hotObservable = new Subject();

Example:

const debouncedObservable = inputObservable.pipe(debounceTime(300));

Example:

const scheduledObservable = observable.pipe(delay(1000, asyncScheduler));

Example:

const finalizedObservable = observable.pipe(finalize(() => console.log('Observable completed')));

Example:

const replaySubject = new ReplaySubject(2); replaySubject.next('First value'); replaySubject.next('Second value'); replaySubject.subscribe(value => console.log(value));

Example:

const behaviorSubject = new BehaviorSubject('Initial value'); behaviorSubject.next('Updated value'); behaviorSubject.subscribe(value => console.log(value));

Example:

const debouncedObservable = inputObservable.pipe(debounce(() => timer(300)));