[Solved] What will be logged to the console when this code runs?import { of } from 'rxjs';... What will be logged to the console when this code runs?import { of } from 'rxjs'; | Angular

Angular - RxJS Operators

What will be logged to the console when this code runs?

import { of } from 'rxjs';
import { tap, map } from 'rxjs/operators';

of(1, 2, 3).pipe(
  tap(x => console.log('Before map:', x)),
  map(x => x * 2),
  tap(x => console.log('After map:', x))
).subscribe();

ABefore map: 2 After map: 2 Before map: 4 After map: 4 Before map: 6 After map: 6

BBefore map: 1 After map: 2 Before map: 2 After map: 4 Before map: 3 After map: 6

CBefore map: 1 Before map: 2 Before map: 3

DAfter map: 2 After map: 4 After map: 6

Step-by-Step Solution

Solution:

Step 1: Trace the observable emissions
The observable emits 1, 2, 3 in sequence.
Step 2: Understand tap and map order
The first tap logs original values before map doubles them. The second tap logs doubled values after map.
Final Answer:
Before map: 1 After map: 2 Before map: 2 After map: 4 Before map: 3 After map: 6 -> Option B
Quick Check:
tap logs before and after map = Before map: 1 After map: 2 Before map: 2 After map: 4 Before map: 3 After map: 6 [OK]

Quick Trick: tap logs values at its position in pipe chain [OK]

Common Mistakes:

MISTAKES

Assuming tap changes values
Ignoring order of operators
Expecting only one tap log per value

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More Angular Quizzes

What will be logged to the console when this code runs?

Step 1: Trace the observable emissions

Step 2: Understand tap and map order

Final Answer:

Quick Check:

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