The answer
Create a class extending Error: class TimeoutError extends Error { constructor(ms) { super(`timed out after ${ms}ms`); this.name = 'TimeoutError'; } }. Then reject with new TimeoutError(ms) in the timeout promise.
Implementing Timeout with Promises in JavaScript
How do you create a custom TimeoutError in JavaScript?
More FAQs in Implementing Timeout with Promises in JavaScript
Use Promise.race: race the operation against a timeout promise. Promise.race([fetch('/api'), new Promise((_, reject) => setTimeout(() => reject(new Error('timeout')), 5000))]). If the timeout fires first, the race rejects.
Use AbortController: const controller = new AbortController(); fetch(url, { signal: controller.signal }). Set a timeout to call controller.abort(). This actually cancels the fetch, not just races it.
To avoid a memory leak. The timeout promise's timer keeps running even after the race settles. clearTimeout cancels the timer. Use try/finally to clear it regardless of outcome.
Still have questions?
Browse all our FAQs or reach out to our support team
Want to upskill yourself?
Your learning library
Small steps. Big possibilities.
Find your next course. Build something great.