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Which statement about forkJoin is true in Angular?

easy🧠 Conceptual Q2 of 15
Angular - RxJS Operators
Which statement about forkJoin is true in Angular?
AIt emits values continuously as observables emit
BIt emits only once after all observables complete
CIt emits the first value from each observable immediately
DIt merges observables without waiting for completion
Step-by-Step Solution
Solution:

  1. Step 1: Understand forkJoin behavior

    forkJoin waits for all source observables to complete and then emits their last emitted values as an array.

  2. Step 2: Contrast with other operators

    Unlike combineLatest, it does not emit continuously but only once after completion.

  3. Final Answer:

    It emits only once after all observables complete -> Option B

  4. Quick Check:

    forkJoin behavior = A [OK]
Quick Trick: forkJoin emits once after all observables complete [OK]
Common Mistakes:
MISTAKES
  • Thinking forkJoin emits multiple times
  • Confusing forkJoin with combineLatest
  • Assuming forkJoin emits before completion

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