Function groupBy

packages/client/src/runtime/mergeBy.ts:24–33

(arr: T[], cb: (element: T) => string)

}

const groupBy = <T>(arr: T[], cb: (element: T) => string): { [key: string]: T[] } => {
  return arr.reduce<{ [key: string]: T[] }>((acc, curr) => {
    const key = cb(curr)
    if (!acc[key]) {
      acc[key] = []
    }
    acc[key].push(curr)
    return acc
  }, {})
}