Struggling with 'await' in loops? Explore common mistakes and modern solutions to optimize async code for performance.

Matt Smith

Common pitfalls when using await in loops include sequential execution bottlenecks and mishandling promises in map(). Sequential for...of loops block execution, while Promise.all() enables parallel execution but fails fast on any rejection. Promise.allSettled() provides safer batch processing by handling both successes and failures. For controlled concurrency respecting API limits, throttling utilities like p-limit offer a middle ground. The forEach() method should never be used with async/await as it doesn't wait for promises to resolve.

Rethinking async loops in JavaScript

Don’t await inside map() unless you mean to

Promise.all() fails fast, even if just one call breaks

<p>Surprisingly, that perfectly matched what I’ve writen before. After change the for each with await to .map() with Promise.allSettled, the performance of the script get faster ^^</p>
