Frontend AlgoArena & Practice Challenges
A practice arena built for frontend engineers. 150 hand-written problems across arrays and objects, async and promises, functions and closures, data structures, and DOM utilities — every one graded against real tests in your browser.
150 Problems
Frontend DSA AlgoArena
44
Easy Fundamentals
66
Medium Core System DSA
40
Hard Advanced DSA
Build your own groupBy
Turn a flat array of records into an object keyed by whatever field you choose — the utility you end up rewriting on every project.
Write debounce from scratch
Stop a function firing on every keystroke. The classic interview question, and the thing that makes search boxes usable.
Retry a request with backoff
Flaky networks are normal. Retry a failing promise a few times, waiting longer after each attempt.
Compare two objects properly
Why does `{a:1} === {a:1}` return false? Write the deep comparison that answers what you actually meant.