JavaScript provides several Promise combinators for handling multiple async operations. Here's how to use them.
Promise.all
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Promise.allSettled
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Promise.race
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Promise.any
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Promise.resolve and Promise.reject
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Practical Patterns
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Error Handling
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Best Practices
Choosing Methods:
✓ Promise.all - all must succeed
✓ Promise.allSettled - need all results
✓ Promise.race - first to settle
✓ Promise.any - first to succeed
Error Handling:
✓ Always handle rejections
✓ Use specific error types
✓ Add timeouts to prevent hanging
✓ Log errors appropriately
Performance:
✓ Parallelize independent operations
✓ Limit concurrency for resources
✓ Batch large operations
✓ Cancel unnecessary requests
Avoid:
✗ Unhandled promise rejections
✗ Infinite parallel requests
✗ Forgetting await
✗ Nested promise chains
Conclusion
Promise combinators enable powerful async patterns. Use Promise.all when all operations must succeed, Promise.allSettled when you need all results regardless of outcome, Promise.race for timeouts and first-response patterns, and Promise.any for fallback strategies. Combine these with proper error handling for robust async code.