JS Practice — Built-in Objects

Object.groupBy() — empty array

📖 Usage Example

// Group array items by a computed key
const items = [{ type: 'a', v: 1 }, { type: 'b', v: 2 }, { type: 'a', v: 3 }]
Object.groupBy(items, item => item.type)
// → { a: [{...}, {...}], b: [{...}] }

Use Object.groupBy() to group an array's elements into an object keyed by a value returned from a callback.

Object.groupBy() — empty input

Calling Object.groupBy with an empty array returns an empty object {}.

Challenge: Implement groupEmpty() that calls Object.groupBy([], () => 'x') and returns the result.

groupEmpty() // → {}

💡 Hints (1)

• An empty iterable always results in no groups.