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Which RxJS operator runs all inner tasks at the same time and emits results as they complete, without waiting for order?

easy🧠 Conceptual Q11 of 15
Angular - RxJS Operators
Which RxJS operator runs all inner tasks at the same time and emits results as they complete, without waiting for order?
A<code>switchMap</code>
B<code>concatMap</code>
C<code>exhaustMap</code>
D<code>mergeMap</code>
Step-by-Step Solution
Solution:

  1. Step 1: Understand mergeMap behavior

    mergeMap subscribes to all inner observables immediately and merges their outputs as they arrive.

  2. Step 2: Compare with other operators

    concatMap waits for each inner observable to complete before starting the next, exhaustMap ignores new inner observables if one is active, and switchMap cancels previous inner observables.

  3. Final Answer:

    mergeMap -> Option D

  4. Quick Check:

    Runs all tasks at once = mergeMap [OK]
Quick Trick: All tasks at once means mergeMap [OK]
Common Mistakes:
MISTAKES
  • Confusing concatMap with mergeMap because both handle multiple tasks
  • Thinking exhaustMap runs all tasks simultaneously
  • Mixing switchMap behavior with mergeMap

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