The library

Pick a Challenge for the role.

Each Challenge is a small JavaScript task graded by a test suite. You see the test names, not the test code. It runs in the browser. No account and nothing to install. Try one yourself, then send it to a candidate.

9 Challenges, all JavaScript

Implement debounceA burst of calls becomes the last one.25 min suggested · 5 required tests · 1 bonus
Implement throttleThe first call runs. The rest wait their turn.25 min suggested · 6 required tests
Implement an LRU cacheKeep what was just used. Drop what went quiet.30 min suggested · 6 required tests · 1 bonus
Implement an event emitterSubscribe, unsubscribe, and stay safe while it is all happening.20 min suggested · 6 required tests · 2 bonus
Parse and build a query stringTurn ?a=1&a=2 into data, and data back into a URL.25 min suggested · 7 required tests · 1 bonus
Implement deep equalityDecide if two values are the same thing, all the way down.25 min suggested · 7 required tests · 1 bonus
Build a rate limiterAllow a burst, then a steady trickle.25 min suggested · 7 required tests · 1 bonus
Retry with backoffCall again, wait longer each time, then give up honestly.30 min suggested · 7 required tests · 1 bonus
Run tasks with a concurrency limitFifty uploads, but only three at a time.35 min suggested · 6 required tests · 1 bonus

Hiring for one of these?

Send a candidate a link to any Challenge. You get back their submitted code, the tests it passed, and how the code arrived.

Send a hiring link

Portfolio Pro

Loading page…