Product limit: zero is a setting
An admin panel reads a product limit from an API. Return fallback only when value is null; the JS function should also handle undefined, which JSON fixtures cannot…
Solve challenge → No login requiredJAVASCRIPT IN PRACTICE
Real-life challenges
Scenarios from real applications: carts, API data, reservations, permissions and file imports. Pick a level and solve a concrete problem.
- API data
- Business rules
- Edge cases
First challenge without login · Free
Selected challenges to get started
Pick a challenge and explore the rules through a concrete example.
The webhook arrived twice
Reject repeated ids for ttl milliseconds after their last acceptance. events are ordered by non-decreasing integer time and have string ids. Accept the first occurrence…
Solve challenge → No login requiredIs shipping free?
A store offers free shipping at threshold or above. Return 0 if total reaches the threshold, otherwise fee. All amounts are non-negative integer cents; total is the cart…
Preview challenge → Free account required to solveReady for more?
Available challenges: 55.
See all challenges →The full catalogue requires a free account.
How should you approach these challenges?
Practical JavaScript challenges cover application scenarios such as carts, bookings, data imports and event handling. You practise translating business requirements into code that also handles exceptions, such as receiving the same webhook twice.
Treat the description as a real application requirement. Identify rules that must always hold, such as avoiding double charges or handling zero correctly. Break them into small steps and compare them with the tests. Consider missing data, repeated events and operation order when relevant to the scenario.
Put it into practice: Product limit: zero is a setting →
Solve this challenge without creating an account.