custom groupBy

groupBy.ts

export function groupBy(collection: any[], iteratee: string) {
  return collection.reduce((result, value) => {
    if (!value.hasOwnProperty(iteratee)) return result

    const key = value[iteratee]

    if (!result || !result[key]) {
      result[key] = [value]
      return result
    }

    result[key] = [...result[key], value]
    return result
  }, {})
}