Which of the following is the correct syntax to transform an observable's values by doubling them using map?

easy📝 Syntax Q3 of 15

Angular - RxJS Operators

Which of the following is the correct syntax to transform an observable's values by doubling them using map?

Asource$.pipe(map(value) => value * 2)

Bsource$.map(value => value * 2)

Csource$.pipe(map => value * 2)

Dsource$.pipe(map(value => value * 2))

Step-by-Step Solution

Solution:

Step 1: Recall correct map usage inside pipe()
The map operator is used inside pipe with a function parameter like map(value => value * 2).
Step 2: Identify syntax errors in other options
source$.map(value => value * 2) uses map directly on observable which is invalid. Options C and D have incorrect arrow function syntax.
Final Answer:
source$.pipe(map(value => value * 2)) -> Option D
Quick Check:
Correct map syntax = pipe(map(fn)) [OK]

Quick Trick: Use pipe(map(value => ...)) for transformations [OK]

Common Mistakes:

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