You have two HTTP calls in Angular returning observables: getUser() and getOrders(). You want to display user info immediately and update orders live as they change. Which combination should you use?
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Angular - RxJS Operators
You have two HTTP calls in Angular returning observables: getUser() and getOrders(). You want to display user info immediately and update orders live as they change. Which combination should you use?
AUse <code>forkJoin</code> for <code>getUser()</code> and <code>combineLatest</code> for <code>getOrders()</code> to combine results.
BUse <code>forkJoin</code> to wait for both HTTP calls to complete before displaying anything.
CUse <code>combineLatest</code> on both observables to get live updates for user and orders.
DUse <code>combineLatest</code> for <code>getUser()</code> and <code>forkJoin</code> for <code>getOrders()</code> to combine results.
Step-by-Step Solution
Solution:
Step 1: Understand HTTP observables behavior
HTTP calls like getUser() usually emit once and complete. Orders may update live, so getOrders() is likely a stream emitting multiple times.
Step 2: Choose appropriate combinators
Use forkJoin for getUser() to wait for the single response. Use combineLatest for getOrders() to get live updates. Then combine these appropriately (e.g., nest or switchMap) to show user info immediately and update orders live.
Final Answer:
Use forkJoin for getUser() and combineLatest for getOrders() -> Option A
Quick Check:
Single HTTP = forkJoin, live stream = combineLatest [OK]
Quick Trick:Use forkJoin for single HTTP, combineLatest for live streams [OK]
Common Mistakes:
MISTAKES
Using combineLatest for single HTTP call causing unnecessary updates
Using forkJoin for live streams causing no updates after first emit
Mixing combinators incorrectly causing delayed or missing data
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