How can you combine map with filter to emit only doubled even numbers from an observable emitting 1 to 5?

hard🚀 Application Q9 of 15

Angular - RxJS Operators

How can you combine map with filter to emit only doubled even numbers from an observable emitting 1 to 5?

Asource$.pipe(filter(x => x % 2 === 0), map(x => x * 2))

Bsource$.pipe(map(x => x * 2), filter(x => x % 2 === 0))

Csource$.pipe(map(x => x % 2 === 0), filter(x => x * 2))

Dsource$.pipe(filter(x => x * 2), map(x => x % 2 === 0))

Step-by-Step Solution

Solution:

Step 1: Filter even numbers first
Use filter(x => x % 2 === 0) to keep only even numbers (2 and 4).
Step 2: Then double the filtered numbers
Apply map(x => x * 2) to double the filtered values, resulting in 4 and 8.
Final Answer:
source$.pipe(filter(x => x % 2 === 0), map(x => x * 2)) -> Option A
Quick Check:
Filter then map for even doubled numbers = source$.pipe(filter(x => x % 2 === 0), map(x => x * 2)) [OK]

Quick Trick: Filter first, then map for correct sequence [OK]

Common Mistakes:

MISTAKES

Master "RxJS Operators" in Angular

9 interactive learning modes - each teaches the same concept differently

Want More Practice?

15+ quiz questions · All difficulty levels · Free

More Angular Quizzes