groupBy

groupBy<
T,
K extends string | number | symbol,
>(
array: T[],
keySelector: (item: T) => K,
): Record<K, T[]>

Source: array.ts:33

Groups array elements by a key selector

Type Parameters

T — Array element type
K extends string | number | symbol — Key type (must be string | number | symbol)

Parameters

array (T[]) — The input array
keySelector ((item: T) => K) — Function to extract the grouping key

Returns

Record<K, T[]> — Object with grouped elements

Example

CODE

const users = [
  { name: 'Alice', age: 25 },
  { name: 'Bob', age: 30 },
  { name: 'Charlie', age: 25 }
]

groupBy(users, u => u.age)
// { 25: [{ name: 'Alice', age: 25 }, { name: 'Charlie', age: 25 }], 30: [{ name: 'Bob', age: 30 }] }