JavaScript Challenges

sumScores(players) adds up every player's score. A player with no score counts as 0. Example: [{ score: 10 }, {}, { score: 5 }] → 15.

Null / Undefined

firstChunk(arr, size) returns the first size items of the array. Example: firstChunk([1, 2, 3, 4, 5], 3) → [1, 2, 3].

Off-by-one

calculateTotal(items) adds up item.price for every item. The prices arrive as text, like "10". Example: prices "10" and "20" → 30.

Type error

delayedDouble(n) waits a moment, then gives back n doubled. Calling code uses await. Example: await delayedDouble(5) → 10.

Async race condition

getLastNItems(arr, n) returns the last n items of the array. Example: getLastNItems([1, 2, 3, 4, 5], 2) → [4, 5].

Off-by-one

isEven(n) returns true when n is even and false when it is odd. Example: isEven(4) → true, isEven(3) → false.

Logic error

findFirstNegative(nums) returns the first negative number in the array, or null if there is none. Example: findFirstNegative([3, -2, 5]) → -2.

Scope error

getUserCity(user) returns the user's city, or "Unknown" if the user has no address. Example: getUserCity({}) → "Unknown".

Null / Undefined