RxJS Interview Questions and Answers
Ques 1. What is RxJS?
RxJS is a library for reactive programming using Observables, making it easier to compose asynchronous or callback-based code.
Example:
const observable = new Observable(observer => { observer.next('Hello'); });
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Ques 2. Explain what Observables are in RxJS.
Observables are data streams that emit a sequence of values over time. They can be subscribed to, and observers can react to emitted values.
Example:
const observable = new Observable(observer => { observer.next('First'); observer.next('Second'); });
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Ques 3. What is an Observer in RxJS?
An Observer is an interface that defines methods to handle the next, error, and complete events emitted by an Observable.
Example:
const observer = { next: value => console.log(value), error: err => console.error(err), complete: () => console.log('Completed') };
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Ques 4. Explain the concept of operators in RxJS.
Operators are functions that can be applied to Observables to manipulate, transform, and filter the emitted values.
Example:
const modifiedObservable = observable.pipe(map(value => value.toUpperCase()));
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Ques 5. What is the purpose of the 'map' operator in RxJS?
The 'map' operator transforms each value emitted by an Observable by applying a provided function to it.
Example:
const modifiedObservable = observable.pipe(map(value => value * 2));
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