Rethinking Async Loops in JavaScript
10 hours ago
- #JavaScript
- #Performance Optimization
- #Async Programming
- Using `await` in loops can cause sequential execution, leading to inefficiency for independent network calls.
- Avoid using `await` inside `map()` without handling promises, as it returns an array of unresolved promises.
- Use `Promise.all()` with `map()` to run API calls in parallel and get all results at once.
- `Promise.all()` fails fast; a single rejection causes the entire operation to fail.
- For error resilience, use `Promise.allSettled()` to process all results, including failures.
- Handle errors inside the mapping function to prevent unhandled promise rejections.
- Use `for...of` with `await` for sequential execution when order or rate limits matter.
- Use `Promise.all()` with `map()` for parallel execution of independent tasks.
- For controlled concurrency, use throttling utilities like `p-limit` to balance speed and API limits.
- Never use `await` in `forEach()` as it doesn’t wait for async operations to complete.
- Choose the right async pattern based on needs: order (`for...of`), speed (`Promise.all`), safety (`allSettled`), or balance (`p-limit`).