oppi.li
source dump of claude code
1/**
2 * https://tc39.es/ecma262/multipage/fundamental-objects.html#sec-object.groupby
3 */
4export function objectGroupBy<T, K extends PropertyKey>(
5 items: Iterable<T>,
6 keySelector: (item: T, index: number) => K,
7): Partial<Record<K, T[]>> {
8 const result = Object.create(null) as Partial<Record<K, T[]>>
9 let index = 0
10 for (const item of items) {
11 const key = keySelector(item, index++)
12 if (result[key] === undefined) {
13 result[key] = []
14 }
15 result[key].push(item)
16 }
17 return result
18}