Iterate over arrays

I have an array of user IDs and need to run an async check for each ID to refresh their cache. Iterate the array so each ID is processed and any errors are collected; do not block the event loop unnecessarily. Provide the pattern I can drop into my refreshUsers function that returns when all checks finish and includes per-ID success or error.

Before I use this iteration in the nightly job, make the approach obvious to the ops reviewer: show how to process IDs concurrently but with a maximum of five simultaneous requests, ensure errors for one ID don’t stop the rest, and return a summary of successes and failures. Keep the example concise and explain the concurrency choice in one sentence.

I implemented a forEach over user IDs and added await inside its callback; the refresh never completed. The job owner Jack will lose trust if the nightly run keeps hanging. I don’t know whether to switch to for...of, Promise.all, or a concurrency limiter. What caused the hang and what is the best fix that preserves concurrency control?

Repeatedly on projects we write array.forEach with await or use Promise.all for thousands of items and blow memory or rate limits. It wastes hours in production incidents and postmortems. What single habit or small rule change will remove these errors: always use for...of with await, always limit concurrency, or prefer streaming APIs? Explain how to enforce it in code reviews and CI linters.