You don't need bluebird / async

async-functions.js

async function forEachSerial(cb, arr) {
  await arr.reduce(async (prevPromise, value) => {
    await prevPromise;
    return cb(value);
  }, Promise.resolve());
}

async function forEachParallel(cb, arr) {
  await Promise.all(arr.map(cb));
}

async function forEachParallelWithLimit(cb, size, arr) {
  const chunks = [];

  for(let i = 0; i < arr.length; i += size) {
    chunks.push(arr.slice(i, i + size));
  }

  await forEachSerial(async (chunk) => {
    await forEachParallel(cb, chunk);
  }, chunks);
}

// Inspired by https://github.com/davetemplin/async-parallel/blob/68ccac12b94075252d0a8233756581b381e4b360/index.ts#L133
async function forEachParallelWithConcurrentLimit(cb, size, arr) {
  async function pool(size, task) {
    let active = 0;
    let done = false;
    let errors = [];
    
    return new Promise((resolve, reject) => {
      next();
      
      async function next() {
        const hasNotReachedLimit = active < size;
        while (hasNotReachedLimit && !done) {
          active++;

          try {
            const more = await task();
            const allTasksDone = --active === 0;

            if (allTasksDone && (done || !more)) {
              if (errors.length === 0) {
                resolve();
              } else {
                reject(new Error(`${errors.length} errors`));
              }
            } else if (more) {
              next();
            } else {
              done = true;
            }
          } catch (err) {
            errors.push(err);
            done = true;
            const allTasksDone = --active === 0;

            if (allTasksDone) {
              reject(new Error(`${errors.length} errors`));
            }
          }
        }
      }
    });
  }


  // Copy source array
  arr = arr.slice();
  // Allocate results array
  const result = new Array(arr.length).fill(null);
  
  let i = 0;
  await pool(size, async () => {
    if (arr.length > 0) {
      const j = i++;
      result[j] = await cb(arr.shift(), j, arr);
    }

    // Has more?
    return arr.length > 0;
  });
}