@tc39-proposal/group-by/index.d.ts

TC39 proposal: Implementation of Object.groupBy and Map.groupBy

declare function groupByMap<T>(array: T[], group: (data: T, index: number) => any): Map<any, T[]>;
declare function groupByObject<T>(array: T[], group: (data: T, index: number) => any): Record<any, T[]>;
declare function groupBy<T>(array: T[], group: (data: T, index: number) => any, map?: boolean): Map<any, T[]> | Record<any, T[]>;
export { groupBy, groupByMap, groupByObject };