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ANPromises can reduce your API response time by 80% using…
Promise.all vs Promise.race vs Promise.allSettled
The problem:
You fetch user data (2 sec), then posts (2 sec), then comments (2 sec). Total = 6 seconds of painful loading screen.
The solutions:
Promise.all - Run all together, wait for everything
When to use: You need all data before showing anything (dashboard loading user profile + activity + notifications simultaneously)
Result: All 3 requests run in parallel. Total time = 2 seconds instead of 6 seconds.
Catch: If ANY request fails, everything fails.
Promise.race - First one to finish wins
When to use: You have backup servers or want timeout protection (try primary API, if it takes too long switch to backup)
Result: Whichever API responds first, you use that. Others get ignored.
Use case: Payment gateway with multiple providers - fastest wins.
Promise.allSettled - Run all, don’t care if some fail
When to use: Some data is optional (loading critical user info + optional analytics + ads)
Result: App works even if ads or analytics API crashes. You get whatever succeeded.
Real impact:
E-commerce product page with 5 API calls: 10 seconds → 2 seconds
with Promise.all
Stop waiting. Start parallelizing.
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( Promise.all JavaScript, async await performance, API optimization, JavaScript promises, parallel API calls, Promise.race, Promise.allSettled, frontend performance, async programming, JavaScript interview )
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