Discussion on: Utils for JavaScript - what do you use regularly?

export async function mapAsync<T, R = T> (
  arr: T[],
  cb: (el: T, i: number, a0: T[]) => Promise<R>,
): Promise<R[]> {
  return Promise.all(arr.map(async (el, i, a0) => {
    return await cb(el, i, a0)
  }))
}

export function distinctBy<T> (arr: T[], k: string, undefinedIsDistinct?: boolean): T[] {
  const arrK = arr.map((a) => hash((a as any)[k]))
  return arr.filter((a, i) => {
    const aK = (a as any)[k]
    if (aK === undefined) {
      return !!undefinedIsDistinct
    } else {
      return arrK.indexOf(hash(aK)) === i
    }
  })
}

export function * chunk<T> (arr: T[], n: number) {
  for (let i = 0; i < arr.length; i += n) {
    yield arr.slice(i, i + n)
  }
}