batch promises (typescript)

batchPromise.ts

static batchPromise(proms: (() => Promise<any>)[], batchSize: number): Promise<void> {
    return this.chunck(proms, batchSize)
      .reduce((step: Promise<any>, chunck) => {
        return step.then(() => {
          return Promise.all(chunck.map(fp => fp()));
        });
      }, Promise.resolve());
  }

  private static chunck<T>(array: T[], batchSize = 5): T[][] {
    const chunked = [];
    for (let i = 0; i < array.length; i += batchSize) {
      chunked.push(array.slice(i, i + batchSize))
    }

    return chunked;
  }