[Solved] What will be logged by the following code?const clicks$ = fromEvent(document, 'click'); clicks$.pipe( switchMap(() => interval(1000).pipe(take(3))) ).subscribe(console.log); | Angular

Angular - RxJS Operators

What will be logged by the following code?

const clicks$ = fromEvent(document, 'click');
clicks$.pipe(
  switchMap(() => interval(1000).pipe(take(3)))
).subscribe(console.log);

AThrows an error because interval is not an Observable

BLogs 0,1,2 once after first click only

CLogs all clicks count without delay

DLogs 0,1,2 every second after each click, cancelling previous intervals

Step-by-Step Solution

Solution:

Step 1: Understand event and interval Observables
Each click triggers switchMap to start a new interval emitting 0,1,2 every second.
Step 2: Effect of switchMap on multiple clicks
New clicks cancel previous intervals, so only latest interval emits values.
Final Answer:
Logs 0,1,2 every second after each click, cancelling previous intervals -> Option D
Quick Check:
switchMap cancels previous inner Observables = A [OK]

Quick Trick: switchMap cancels previous intervals on new clicks [OK]

Common Mistakes:

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What will be logged by the following code?