JavaScript Snippet

Async Queue with Concurrency Limit

Difficulty: Hard

When you have hundreds of API calls but the upstream caps you at 5 in flight, naive `Promise.all` is a 429 storm waiting to happen. A concurrency-limited queue runs at most `n` tasks at once, draining a backlog as workers free up. This snippet starts with the minimal worker pool, adds per-task error isolation, then layers in cancellation and ordered results so the helper holds up in production.